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United States 
Environmental Protection 
Agency 


EPA/625/3-87/013 
July 1988 


SrEPA Special Report on 

Ingested Inorganic 










Special Report on 
Ingested Inorganic Arsenic 


Skin Cancer; Nutritional Essentiality 


Principal Authors 


Tina Levine, Ph.D. William Marcus, Ph.D. 

Amy Rispin, Ph.D. Office of Drinking 

Cheryl Siegel Scott, M.S.P.H. Water 
Office of Pesticides and 
Toxic Substances 


Chao Chen, Ph.D. 
Herman Gibb, M.P.H 
Office of Research 
and Development 


Technical Panel 


Chao Chen, Ph.D. 

Herman Gibb, M.P.H. 

Frank Gostomski, Ph.D., Chairman 
Tina Levine, Ph.D. 


William Marcus, Ph.D. 

Amy Rispin, Ph.D. 

Reva Rubenstein, Ph.D. 
Cheryl Siegel Scott, M.S.P.H. 


Risk Assessment Forum Staff 

Dorothy E. Patton, Ph.D., J.D., Executive Director 
Judith S. Beilin, Ph.D., Science Coordinator 
Linda C. Tuxen, B.S., Technical Liaison 


RISK ASSESSMENT FORUM 
U.S. ENVIRONMENTAL PROTECTION AGENCY 
WASHINGTON, DC 20460 





Disclaimer 


This document has been reviewed in accordance with U.S. Environmental 
Protection Agency policy and approved for publication. Mention of trade 
names or commercial products does not constitute endorsement or 
recommendation for use. 


ii 







Contents 


Preface . v 

External Peer Review . vi 

EPA Risk Assessment Forum (1986-87) viii 

EPA Risk Assessment Council (1986-87) viii 

Science Advisory Board Review . x 

I. Overview . 1 

II. Executive Summary . 5 

A. Background . 5 

B. Validity of Data from Taiwan . 6 

C. Biological Considerations for Dose-Response Assessment 6 

D. Dose-Response Assessment . 7 

E. Nutritional Essentiality . 9 

F. Conclusion . 9 

III. Hazard Identification and Epidemiologic Studies Suitable for 

Dose-Response Evaluation . 11 

A. Preliminary Considerations . 11 

B. Review of Studies . 12 

1. Taiwan Study . 12 

2. Mexican Study . 13 

3. German Study . 15 

C. Summary . 16 

IV. Selected Elements of Hazard Identification. 17 

A. Pathologic Characteristics and Significance of 

Arsenic-Induced Skin Lesions . 17 

1. Description and Malignant Potential of Skin Lesions .... 17 

2. Progression of Skin Lesions . 19 

3. Case-Fatality Rate of Arsenic-Induced Skin Cancer ... 19 

B. Genotoxicity . 21 

1. Introduction . 21 

2. Possible Mechanisms of Genotoxicity . 22 

3. The Use of Arsenic Genotoxicity Data in the Evaluation 

of Carcinogenic Risk . 23 

C. Metabolism and Distribution . 24 





iii 





























Contents (continued) 

V. Dose-Response Estimate for Arsenic Ingestion . 27 

A. Introduction . . . . ,. 27 

1. Considerations Affecting Model Selection . 27 

2. Changes in Methodology Relative to the 1984 Assessment 28 

B. Estimation of Risk . 29 

1. Estimation of Risk using Taiwan Data . 29 

2. Comparison with Mexican Data . 29 

3. Comparison with German Data. 30 

C. Summary of Dose-Response Evaluation . 30 

1. Numerical Estimates . 30 

2. Uncertainties . 31 

3. U.S. Populations . 31 

VI. Arsenic as an Essential Nutrient . 33 

A. Background . 33 

B. Animal Studies . 34 

1. Data Summary . 34 

2. Evaluation of Data . 35 

C. Applicability to Humans . 36 

D. Summary and Conclusions. 38 

VII. Future Research Directions . 39 

A. Epidemiologic Studies . 39 

B. Mechanisms of Carcinogenesis for Arsenic-Induced 

Skin Cancer . 39 

C. Pharmacokinetics/Metabolism of Arsenic . 39 

D. Essentiality . 40 

VIII. Appendices 

Appendix A: Summary of Epidemiologic Studies and Case 

Reports on Ingested Arsenic Exposure . 41 

Appendix B: Quantitative Estimate of Risk for Skin Cancer 

Resulting from Arsenic Ingestion . 69 

Appendix C: Internal Cancers Induced by Ingestion 

Exposure to Arsenic . 89 

Appendix D: Individual Peer Review Comments 

on Essentiality. 91 

Appendix E: Metabolic Considerations . 97 

IX. References . 115 


IV 

































Preface 


The U.S. Environmental Protection Agency (EPA) Risk Assessment Forum 
was established to promote scientific consensus on risk assessment issues 
and to ensure that this consensus is incorporated into appropriate risk 
assessment guidance. To accomplish this, the Risk Assessment Forum 
assembles experts from throughout the EPA in a formal process to study and 
report on these issues from an Agency-wide perspective. 

For major risk assessment activities, the Risk Assessment Forum may 
establish a Technical Panel to conduct scientific review and analysis. 
Members are chosen to assure that necessary technical expertise is available. 
Outside experts may be invited to participate as consultants or, if appropriate, 
as Technical Panel members. 

Major scientific controversies have existed for many years within EPA 
concerning the health effects of exposure to ingested arsenic. To help resolve 
these issues, a Technical Panel on Arsenic was formed within EPA by the 
Risk Assessment Forum. The Technical Panel was charged with preparing a 
report on arsenic health effects for Agency-wide concurrence and use. 


V 


! 


External Peer Review 

A draft of this report was reviewed at a peer review workshop of scientific 
experts in Hunt Valley, Maryland, on December 2-3, 1986. The workshop 
was highly instructive for the EPA Technical Panel, and the current draft 
incorporates many of the peer reviewers’ comments. 


Dr. Roy Albert 

Department of Environmental Health 
University of Cincinnati Medical Center 

Dr. Julian B. Andelman 
University of Pittsburgh 
Graduate School of Public Health 

Dr. John Bailar 
Harvard University and 
U.S. Department of Health and Human 
Services 

Dr. Mariano Cebrian 
Department of Pharmacology and 
Toxicology (Mexico) 

Dr. C.J. Chen 
Institute of Public Health 
National Taiwan University 
College of Medicine 

Dr. Philip Enterline 

Center for Environmental Epidemiology 
University of Pittsburgh 

Dr. Kurt J. Irgolic 
Department of Chemistry 
Texas A & M University 


Dr. Ruey S. Lin 
College of Medicine 
National Taiwan University 

Dr. Kate Mahaffey 
National Institute of 

Occupational Safety and Health 

Dr. Daniel B. Menzel 
Department of Pharmacology 
Duke Medical Center 


Dr. Paul Mushak 
Pathology Department 
University of North Carolina 

Dr. Forrest Nielson 
United States Department 
of Agriculture 

Grand Forks Human Nutrition Research 
Center 

Dr. Joseph Scotto 
National Institute of Health 
National Cancer Institute 

Dr. David Strayer 
Department of Pathology 
University of Texas Medical School 


VI 




External Peer Revi( 


Dr. Wen-Ping Tseng 
Department of Medicine 
National Taiwan University 
College of Medicine 


(continued) 

NOV: 5 


Dr-^^ijagdc^yWeiler 
Environment Ontario (Canada) 


di nation 


Dr. Marie Vahter 

National Institute of Environmental 
Medicine 

Karolinska Institute (Sweden) 


The Technical Panel acknowledges with appreciation the special 
contributions of Dr. Vicki Dellarco, Dr. David Jacobson-Kram, Mr. Paul 
White, Dr. Ken Brown, Dr. Kerrie Boyle, and Ms. Pamela Bassford. 


VII 



EPA Risk Assessment Forum (1986-87) 

Drafts of this report were reviewed by EPA’s Risk Assessment Forum in 
October 1986 and in March 1987. In July 1987, the final report was submitted 
to EPA’s Risk Assessment Council for concurrence. 

Forum Members 

Peter W. Preuss, Ph.D., Office of Research and Development, Chairman 
Mary Argus, Ph.D., Office of Pesticides and Toxic Substances 
Donald Barnes, Ph.D., Office of Pesticides and Toxic Substances 
Barbara Beck, Ph.D., Region 1 

Michael Dourson, Ph.D., Office of Research and Development 
William Farland, Ph.D., Office of Research and Development 
Penelope Fenner-Crisp, Ph.D., Office of Pesticides and Toxic Substances 
Richard N. Hill, M.D., Ph.D., Office of Pesticides and Toxic Substances 
Carole Kimmel, Ph.D., Office of Research and Development 
Arnold M. Kuzmack, Ph.D., Office of Water 

Designated Representatives 
James Baker, Region 8 

Timothy Barry, Office of Policy Planning and Evaluation 

Arnold Den, Region 9 

Kenneth Orloff, Region 4 

Maria Pavlova, Region 2 

Patricia Roberts, Office of General Counsel 

Samuel Rotenberg, Region 3 

Reva Rubenstein, Office of Solid Waste and Emergency Response 
Deborah Taylor, Office of the Administrator 
Jeanette Wiltse, Office of Air and Radiation 

EPA Risk Assessment Council (1986-87) 

John A. Moore, Office of Pesticides and Toxic Substances, Chairman 

Daniel P. Beardsley, Office of Policy Planning and Evaluation 

Theodore M. Farber, Office of Pesticides and Toxic Substances 

Victor Kimm, Office of Pesticides and Toxic Substances 

Hugh McKinnon, Office of Research and Development 

William Muszynski, Region 2 

Vaun A. Newill, Office of Research and Development 

Peter W. Preuss, Office of Research and Development 

Rosemarie Russo, Office of Research and Development 


VIII 



EPA Risk Assessment Council (1986-87) - 

(continued) 

Deborah Taylor, Office of the Administrator 
Stephen R. Wassersug, Region 3 
Donald Clay, Office of Air and Radiation 
Michael Cook, Office of Water 

Marcia Williams, Office of Solid Waste and Emergency Response 
Terry Yosie, Office of the Administrator 


IX 


U.S. Environmental Protection Agency 
Science Advisory Board Review 


The Science Advisory Board’s (SAB) Environmental Health Committee was 
asked to review the Risk Assessment Council’s science policy statement in 
the November 1987 draft report that recommended modification of the Risk 
Assessment Forum’s skin cancer risk estimate. The SAB advised the Council 
that the request was beyond the scope of its activities and was unable to 
comply. 


Chairperson 

Dr. Richard A. Griesemer 
Director, Biology Division 
Oak Ridge National Laboratory 
Oak Ridge, Tennessee 


Members 

Dr. Seymour Abrahamson 
Professor of Zoology and Genetics 
University of Wisconsin 
Madison, Wisconsin 


Dr. Gary P. Carlson 
Professor of Toxicology 
School of Pharmacology and 
Pharmacy Science 
Purdue University 
West Lafayette, Indiana 

Dr. John Doull 

Professor of Pharmacology and 
Toxicology 

University of Kansas Medical Center 
Kansas City, Kansas 

Dr. Philip E. Enterline 
Professor of Biostatistics 
University of Pittsburgh 
Pittsburgh, Pennsylvania 


Executive Secretary 
Dr. Rick Cothern 

Science Advisory Board (A-101F) 
U.S. Environmental Protection 
Agency 

Washington, D.C. 


Dr. E. Marshall Johnson 
Professor 

Department of Anatomy 
Jefferson Medical College 
Philadelphia, Pennsylvania 

Dr. Nancy Kim 

Director, New York Dept, of Health 
Bureau of Toxic Substances 
Management 
Albany, New York 

Dr. Warner D. North 
Principal 

Decision Focus, Inc. 

Los Altos, California 


Dr. Robert Tardiff 
Principal 

Environ Corporation 
Washington, D.C. 


X 


Science Advisory Board Review (Continued) 


Members (Continued) 


Dr. Bernard Weiss 
Professor, Division of Toxicology 
University of Rochester 
Rochester, New York 


Dr. Ronald E. Wyzga 
Program Manager 
Electric Power Research Institute 
Palo Alto, California 


XI 












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I. Overview 


Arsenic exposure has long been associated with several different forms of 
human cancer. The association between inhaled arsenic and an elevated risk 
of lung cancer is well documented (Enterline and Marsh, 1980; Lubin et al., 
1981; Welch et al., 1982; Lee-Feldstein, 1983). Other studies have reported 
an association between ingested inorganic arsenic and an increased 
incidence of nonmelanoma skin cancer in a Taiwanese population (Tseng et 
al., 1968; Tseng, 1977; hereafter "Taiwan study") (Appendix A). Also, 
exposure to ingested arsenic is associated with an elevated but unquantifiable 
risk for cancer of internal organs (e.g., liver, kidney) in some studies (Chen et 
al., 1985, 1986). 

The U.S. Environmental Protection Agency’s Health Assessment 
Document (HAD) for Inorganic Arsenic (U.S. EPA, 1984a) contained 
qualitative and quantitative carcinogen risk assessments for both inhalation 
and ingestion routes of exposure. Several EPA offices raised questions about 
the assessment for the ingestion exposure, including: the validity of the 
Taiwan study and applicability of the dose-response assessment to the U.S. 
population, the interpretation and use of arsenic-associated skin lesions, and 
the role of arsenic in human nutrition (the "essentiality" issue). 

A Technical Panel was convened by the Risk Assessment Forum to 
address these issues. In the course of its deliberations, the Technical Panel 
examined several other issues relating to hazard identification and dose- 
response assessment for arsenic-induced skin cancer, including some 
aspects of the pathology of arsenic-associated skin lesions, the genotoxicity 
of arsenic, the metabolism, body burden, and distribution of this element, and 
the possibility of threshold effects. The Technical Panel’s findings are 
summarized in the Executive Summary (Part II) and detailed in the remainder 
of this report. Additional technical analyses appear in the five appendices. 

A draft of the Technical Panel’s Special Report was peer reviewed at a 
public workshop held in Hunt Valley, Maryland, on December 2-3, 1986. The 
Panel revised its report in line with many helpful peer review comments and 
presented a revised document to the Risk Assessment Forum on March 27, 
1987. The Forum’s comments and recommendations have been incorporated. 

This report is designated as a "Special Report" to distinguish this analysis, 
which is deliberately limited to the skin cancer and nutritional essentiality 
issues identified above, from comprehensive risk assessments that fully 
analyze all indicated health effects and fully conform with EPA’s Guidelines 
for Carcinogen Risk Assessment (U.S. EPA, 1986; hereafter "cancer 
guidelines"). The Special Report addresses many of the hazard identification. 


1 


dose-response assessment (Appendix B), and risk characterization 
parameters called for in the cancer guidelines, but it does not fully assess or 
characterize arsenic risks for skin cancer nor does it analyze the other 
cancers associated with exposure to this element. 

Agency scientists and decision-makers should be aware that the lifetime 
cancer risks and other analyses in this report apply to a form of cancer that is 
treatable and that generally has a good survival rate in the United States. For 
this reason, the estimates for arsenic-induced skin cancer may have 
different implications for human health status than comparable numerical 
estimates would have for more fatal forms of cancer, including arsenic- 
induced lung cancer for which the lifetime cancer risk is 4.3 x 10*3 per 
iig/cubic meter. Because an examination of the regulatory significance of this 
difference was beyond the purview of the Risk Assessment Forum, the Forum 
directed this question to EPA’s Risk Assessment Council. 

The Council’s comments and guidance for Agency decisions on 
arsenic-related skin cancer risk were endorsed by EPA Administrator Lee M. 
Thomas in a June 21, 1988 memorandum to EPA offices. 

Summary 

For several years the Agency has debated the issue of the 
carcinogenicity risk associated with the ingestion of inorganic arsenic. Last 
year, the Risk Assessment Forum (Forum) completed a reassessment of the 
problem and issued its finding in a Special Report on Arsenic. The Report, 
which was extensively peer-reviewed by outside experts, concludes that, 
based on the scientific data available and in keeping with the Agency’s Risk 
Assessment Guidelines, the cancer potency (slope factor) for human 
ingestion of inorganic arsenic should be in the range of 3 to 7 x lO'^ 
(pg/L)*L This is a reduction of about one order of magnitude from the 
estimate generated in 1984 and reflects a more detailed analysis of the 
available scientific data. To facilitate implementation of the reassessment, I 
am adopting the Risk Assessment Council’s (Council) recommendation that 
a single value of 5 x 10'5 (pg/L)-i be used. 

The Council discussed a series of important issues which go beyond the 
factors considered when EPA quantifies carcinogenic risks. The Council went 
on to recommend that in making case-specific risk management decisions, 
program offices should be aware of qualities and uncertainties of a 
carcinogenic risk estimate for ingested inorganic arsenic that might mitigate 


■•There is evidence of an association between arsenic ingestion and an elevated risk 
of cancer of various internal organs (e.g., lung, liver, bladder) (see Part III, Section 
A and Appendix C). This association is not discussed in detail in this report because 
information needed to quantify the dose-response for internal cancers was not 
available. As developed in Parts V and VI, the available information merits 
consideration in the overall assessment of arsenic risk to humans, and further 
research is warranted. 

The skin cancer analysis presented here, as well as the ancillary issues discussed 
in connection with this analysis, supersedes corresponding discussions in the 1984 
HAD. The Panel recommends, however, that EPA offices consult the HAD for 
information on the other forms of arsenic-induced cancer and other arsenic health 
effects. Also, as explained in the cancer guidelines (U.S. EPA, 1986), appropriate 
exposure information must be considered along with the’ health effects data to 
develop complete risk assessments for this element. 


2 



their concerns compared to estimates of risks for other carcinogens. In the 
Council’s view, these qualities and uncertainties could, in a specific risk 
management situation, modify one’s concern downwards as much as an 
order of magnitude. In such instances, the management document must 
clearly articulate this fact and state the factors that influenced such a 
decision. 

Background 

There is general agreement that inhalation of inorganic arsenic is 
associated with the development of lung tumors in humans. The available 
data are adequate to quantitatively estimate the magnitude of the associated 
risks. 

The case of ingestion of inorganic arsenic is more complicated and has 
been the source of considerable controversy. First, the principal scientific 
evidence of human carcinogenicity of ingested arsenic is found in a series of 
epidemiologic studies which were conducted in other countries and whose 
appropriateness to the assessment of risk to the U.S. population has been 
called into question. Second, the primary tumor response in these human 
studies is skin tumors, which are more likely to be detected and successfully 
treated and much less likely to lead to death than are the lung tumors 
associated with arsenic exposure via the inhalation route. Third, limited 
animal evidence suggests that arsenic might be an essential nutrient, 
although there are no relevant human data at this time. It has been argued 
that taking action to reduce the level of arsenic below some critical level (as 
yet unspecified) may reduce any potential cancer risk only at the expense of 
other decrements to human health. 

These difficulties in assessment have led to a range of interpretations and 
positions in different offices and different Regions. Therefore, the matter was 
referred to the Risk Assessment Forum for consideration. 

Risk Assessment Forum Special Report on Arsenic 

The Forum worked diligently to address these issues and others that 
arose during the deliberations. The considerable efforts of Agency scientists 
were supplemented by a workshop involving an international panel of experts 
on the subject, including some of the authors of the principal studies. As a 
result, the Forum was able to resolve many issues, to the extent permitted by 
science. Extensive peer reviews, both internal and external, concurred with 
the conclusions of the Forum. 

In summary, the Forum concluded that a series of studies conducted in 
Taiwan on a large human population that ingested inorganic arsenic in 
drinking water, together with confirmatory studies in other locations, 
demonstrates that arsenic is a human carcinogen by the oral route, which 
puts the chemical in Category A of the Agency’s scheme for designating the 
weight-of-evidence. Further, the Forum concluded that the Taiwan studies 
provide a reasonable basis for quantitatively assessing the risk of skin cancer 
asspciated with the ingestion of inorganic arsenic in this country, despite 
many uncertainties. 

Employing methods in keeping with the Risk Assessment Guidelines, the 
Forum used the Taiwanese data and estimated the cancer potency (slope of 
the dose-response curve) to be 3 to 7 x 10*5 (pg/L)-T This range is 
roughly an order of magnitude less than the slope factor calculated in 1984. 
The change primarily reflects modifications in risk assessment methodology 
and better estimates of the exposures involved in the epidemiology studies 
used to estimate potency. 

The Forum noted that the slope of the dose-response curve may be less 
than linear and might not pass through the origin. In such a case the 
calculated slope factor would overestimate the true risk. 

The Forum reaffirmed the finding that the skin tumors expected from this 
exposure would, most often, not result in death. The Forum noted, but did not 
explore in depth, the existence of data suggesting a link between human 


3 


ingestion of inorganic arsenic and the occurrence of internal cancers. Finally, 
the report concludes that while it is plausible that arsenic is a nutritional 
requirement in animals and a possible requirement in humans, additional 
studies are needed to decide the question definitively. 

Risk Assessment Council Action 

In a series of meetings, the Council discussed the Forum’s Special 
Report, which they found to contain a solid analysis of the science, a clear 
consensus on the conclusions, and a discussion of the data gaps and 
associated uncertainties. The Council approved the Report as submitted. The 
Report represents considerable progress in consolidating a consistent 
Agency view on the risks of ingested inorganic arsenic, but uncertainties 
remain which would permit a range of interpretations of the science. 

First, the Council believes that, from an implementation point of view, the 
potency is better expressed as a single value, 5 x 10'5 (pg/L)-^ rather 
than a range. This is particularly true in this case where the range is small; 

i.e., 3 to 7 X 10-5 (pg/L)-T 

Second, the Council believes that the uncertainties which are currently 
unresolvable on a scientific basis are best accounted for in the risk 
management portion of the decision-making process. Specifically, on a 
case-specific basis, the Council recommends that risk managers reach their 
judgments in light of the knowledge that: 

1. Ingested inorganic arsenic is a class A carcinogen resulting in an 
increased incidence of skin cancers. 

2. Only a fraction of the arsenic-induced skin cancers are fatal. 

3. The non-fatal skin cancers remain of some concern. 

4. The dose-response curve for the skin cancers may be sublinear, in 
which case the cancer potency in this Report will overestimate the 
risks. 

5. Arsenic may cause cancer in internal organs. 

6. Arsenic is a possible but not proven nutritional requirement in 
animals. There are no direct data on the essentiality of arsenic in 
humans. 

Conclusion 

Based on the Risk Assessment Council’s review of the Forum’s Report 
on inorganic arsenic, I am recommending that: 

a. Risks of skin cancers associated with the ingestion of inorganic 
arsenic be estimated using a cancer potency (slope factor) of 5 x 
10-5 (ijig/L)-i, derived in the Forum’s Special Report. 

b. In reaching risk management decisions in a specific situation, risk 
managers must recognize and consider the qualities and 
uncertainties of risk estimates. The uncertainties associated with 
ingested inorganic arsenic are such that estimates could be modified 
downwards as much as an order of magnitude, relative to risk 
estimates associated with most other carcinogens. In such instances, 
the management document must clearly articulate this fact and state 
the factors that influenced such a decision. 


4 


II. Executive Summary 


A. Background 

A Technical Panel of the U.S. Environmental Protection Agency’s Risk 
Assessment Forum has studied three special issues regarding certain health 
effects, particularly skin cancer, associated with arsenic ingestion: (1) the 
validity of the Taiwan study and its use for dose-response assessment in the 
U.S. population, (2) the interpretation and use of skin lesions reported as 
arsenic-induced skin cancers, and (3) the role of arsenic as an "essential" 
nutritional requirement in the human diet. The Technical Panel also reviewed 
auxiliary information on genotoxicity, metabolism, and other factors that might 
suggest the most appropriate approach to dose-response assessment. 

In brief summary, the analysis shows a causal relationship between 
ingestion exposure to arsenic and an increased risk of skin cancer. This leads 
to classification of this element as a Group A human carcinogen under EPA’s 
cancer guidelines (U.S. EPA, 1986). Analyses of data on genotoxicity, 
metabolism, and pathology yielded information on possible carcinogenic 
mechanisms for arsenic. However, there is not sufficient information to 
evaluate a dose-response according to any specific mechanism that one 
may postulate. In the absence of fully persuasive evidence for any of the 
possible mechanisms, a generalized multistage model that is linear at low 
doses was used to place an upper bound on the , expected human cancer 
dose-response. 

Using data from a human population for which the lowest dose level in 
drinking water was approximately 10 pg/kg/day, the maximum likelihood 
estimate (MLE) of skin cancer risk for a 70-kg person consuming 2 liters of 
water per day contaminated with 1 pg/L arsenic ranges from 3 x 10*5 (based 
on Taiwanese females) to 7 x 10*5 (based on Taiwanese males). In other 
terms, the MLE of risk due to 1 iig/kg/day of arsenic intake ranges from 1 x 
10*3 to 2 X 10*3. These estimates are about an order of magnitude lower 
than those presented in the 1984 HAD. These risk estimates are based on a 
dose-response model that assumes linearity at low doses and would 
overestimate risk if risk decreases faster than linear at low doses or if a 
threshold for arsenic-induced skin cancer exists. 

The available data on nutritional "essentiality" do not fully resolve the 
questions raised. Arsenic is a possible but not proven nutritional requirement 
in animals. If arsenic Is In fact an essential nutrient In animals. It is likely to be 
essential in humans, but there are no data on this issue. If arsenic is essential, 
there is no clear scientific basis for deciding how to use this information in 
relation to the dose-response information. 

This report summarizes the Technical Panel’s review and analysis of 
relevant data. To fully characterize the risk from arsenic exposure in human 
populations, exposure information and the 1984 HAD on the inhalation route 
of exposure must be considered along with the findings in this report. A brief 
synopsis follows. 


5 


B. Validity of Data from Taiwan 

The Technical Panel believes that results from the Tseng et al. (1968) 
and Tseng (1977) studies demonstrate a causal association between arsenic 
ingestion and an elevated risk of skin cancer subject to certain limitations. 
These investigators studied the prevalence of hyperpigmentation, 
hyperkeratosis, and skin cancer in 40,421 residents of 37 Taiwan villages in 
which arsenic in well-water ranged from <0.001 ppm in shallow wells to 
1.82 ppm. The 428 cases of skin cancer (10.6/1,000) showed a clear-cut 
increase in prevalence with exposure. No cases of skin cancer, 
hyperpigmentation, or hyperkeratosis were reported in a comparison 
population of 7,500 people who were essentially not exposed to arsenic in 
drinking water. 

Reliance on these data is based on several considerations; (1) the study 
and comparison populations were large enough (40,421 and 7,500, 
respectively) to provide reliable estimates of the skin cancer prevalence rates; 
(2) a statistically significant elevation in skin cancer risk among the exposed 
population over the comparison population was observed many years after 
first exposure: (3) the data show a pronounced skin cancer dose-response 
by exposure level; (4) the exposed and comparison populations were similar 
in occupational and socioeconomic status, with arsenic-contaminated water 
the only apparent difference between these two groups; and (5) over 70% of 
the observed skin cancer cases were pathologically confirmed. 

There are also important uncertainties in the studies of the Taiwanese 
population, including (1) chemicals other than arsenic in the drinking water, 
which may have confounded the observed association between skin cancer 
and arsenic ingestion; (2) the lack of blinding of the examiners, which may 
have led to a differential degree of ascertainment between the exposed and 
comparison populations; and (3) the role of diet in the skin cancer response 
observed in the exposed population. The influence of these uncertainties 
remains to be determined, but they signal a need for cautious characterization 
of the risk. 

Given the findings in this and other studies (see Appendix A), arsenic is 
classified as a Group A human carcinogen for which there is sufficient evi¬ 
dence from epidemiologic studies to describe a causal association between 
exposure to this agent and human cancer. 

C. Biological Considerations for Dose-Response Assessment 

To develop the dose-response assessment, the Technical Panel 
considered auxilary information on the pathology of arsenic-associated skin 
lesions, genotoxicity, and the metabolism of this element that might shed light 
on biological or chemical processes leading to arsenically induced cancer. 
The Technical Panel looked particularly for information that would help 
determine whether arsenically induced cancer is more appropriately analyzed 
using non-threshold or threshold assumptions, and whether arsenic- 
induced carcinogenicity is linear at low doses. 

The Panel studied the possibility that nonmalignant arsenic-induced skin 
lesions (e.g., hyperpigmentation, hyperkeratosis) occur more frequently at 
exposure levels below which skin cancer is observed, providing a basis for 
analyzing arsenic-induced skin cancer as a threshold phenomenon. The 
Panel found, however, that these lesions are not always precursors to 
malignant lesions and that some malignant lesions arise de novo. Thus, 
characterization of the skin lesions established end points of interest for 
dose-response assessment, and suggested that nonmalignant lesions may 


6 


serve as useful biological markers of exposure to arsenic, but did not resolve 
uncertainties regarding nonthreshold approaches for quantifying arsenical skin 
cancer. 

Data from genotoxicity studies raise a number of questions. Arsenic does 
not appear to induce point mutations, but arsenicals increase the frequency of 
sister chromatid exchanges and chromosome breakage in cultured cells, 
including human cells. Such chromosome breaks could lead to stable 
chromosome aberrations, which require a minimum of two hits with a loss or 
exchange of genetic material, events that would be compatible with nonlinear 
kinetics and, therefore, a sublinear dose-response relationship. 

Information on the absorption, deposition, and excretion of ingested arsenic 
shows that arsenic is handled by enzymatic and nonenzymatic reactions. It 
shows that, except for high exposure levels, inorganic arsenic is converted 
non-enzymatically to arsenite ( + 3). In vivo methylation of arsenic to 
monomethyl and dimethyl arsenic (the latter being the major methylated 
metabolite) appears to be a route of detoxification for acute effects and a 
general route of elimination. Although some data suggest that methylating 
capacity in humans can become saturated, studies to delineate the role of 
biomethylation in chronic arsenic toxicity are needed. Arsenic is known to 
deposit in certain organs, including the skin, liver, lung, and kidney, a pattern 
compatible with arsenic-associated cancer in these organs. 

Scientists at EPA and elsewhere, faced with uncertainty about mechanisms 
of chemical carcinogenesis, often analyze chemical carcinogens as though 
simple genetic changes initiate a carcinogenesis process that is linear at low 
levels of exposure. Extrapolation procedures from high to low doses then 
depend on models that are also linear at low doses. Since for arsenicals, as 
for a number of other carcinogens, there is no evidence of point mutations in 
standard genetic test systems, the single-hit theory for chemical 
carcinogenesis may not be applicable. Similarly, the structural chromosomal 
rearrangements that have been Implicated in some cases of carcinogenesis 
would be expected to require at least two "hits", if not more. In addition, the 
known toxic effects of the inorganic arsenicals are not inconsistent with the 
idea that multiple Interactions are involved in producing adverse cellular 
effects. 

While consideration of these data on the genotoxicity, metabolism, and 
pathology of arsenic has provided information on the possible mechanism by 
which arsenic may produce carcinogenic effects, a more complete 
understanding of these biological data in relation to carcinogenesis is needed 
before they can be factored with confidence into the risk assessment process. 

D. Dose-Response Assessment 

The data from Taiwan have several strengths for quantitative risk 
assessment: (1) the number of persons in the exposed population and the 
comparison populations (40.421 and 7,500, respectively) is large; (2) the 
number of skin cancer cases in the exposed population is relatively large (428 
observed); (3) the skin cancer prevalence rates are reported by 12 different 
age and dose groups; and (4) the data show a pronounced skin cancer 
dose-response. 

At the same time, limitations in the Taiwanese studies introduce 
uncertainties regarding applicability of this information to the U.S. population. 
These uncertainties include: (1) the potential exposure to sources of arsenic 
other than drinking water (e.g., diet) which could result in an overestimation of 
the cancer risk; (2) the higher case-fatality rate and earlier median age of 


7 


onset for Blackfoot disease, which may also be arsenic related, thus resulting 
in an underestimation of cancer risk; and (3) differences in diets other than 
arsenic content, between the Taiwanese and U.S. populations, which could 
modify the carcinogenic response to arsenic observed in Taiwan. (The diet of 
the arsenic-exposed population was reported to be "low in protein and fat 
and high in carbohydrates, particularly rice and sweet potatoes.”) 

Skin cancer cases in these studies included squamous cell carcinoma, 
basal cell carcinoma, in situ squamous cell carcinoma (Bowen’s disease), and 
Type B keratoses, which Yeh (1973) defines as intraepidermal carcinomas. 
Type A keratoses were defined-by Yeh (1973) as benign tumors. Although 
these keratoses are also found in the exposed population and may pose a 
carcinogenic hazard, they were not included in the quantitative estimate of 
cancer risk because of uncertainty regarding their progression to squamous 
cell or basal cell carcinomas. In addition, there was no information on age- 
specific prevalence rates for this lesion. 

The Technical Panel developed the dose-response assessment using a 
multistage extrapolation model that incorporates low-dose linearity. This 
choice was guided by principles laid down by the Office of Science and 
Technology Policy (OSTP, 1985) and in EPA’s cancer guidelines (U.S. EPA, 
1986), which set forth the principles that follow. 

No single mathematical procedure is recognized as the most 
appropriate for low dose extrapolation in carcinogenesis. When 
relevant biological evidence on mechanism of action exists (e.g., 
pharmacokinetics, target organ dose), the models or procedures 
employed should be consistent with the evidence. When data and 
information are limited, however, and when much uncertainty 
exists regarding the mechanism of carcinogenic action, models or 
procedures which incorporate low dose linearity are preferred 
when compatible with the limited information. 

The multistage model chosen by the Technical Panel differed from the 
model used in the Agency’s Health Assessment Document for Inorganic 
Arsenic (U.S. EPA, 1984) in that the current model is both linear and quadratic 
in dose. Other changes between the current model and that presented in 
1984 include the use of a life-table approach in the current analysis to 
calculate a lifetime risk of skin cancer. The previous estimate of risk was a 
lifetime estimate, assuming that an individual lived to be 76.2 years of age. 
The current model uses a maximum likelihood approach whereas the 
previous model was a least squares linear regression of prevalence rates. 
Also, the current analysis assumes that Taiwanese males in the arsenic- 
endemic area of Taiwan drank 75% more water than does the U.S. 
population. The current analysis also estimated a risk from the data on 
Taiwanese females, which was not done in the 1984 analysis and assumed 
that Taiwanese females drink the same amount of water per day as does the 
U.S. population. 

Based on the current model and the Taiwanese data, the MLE of cancer 
risk for a 70-kg person who consumes 2 liters of water per day contaminated 
with 1 tig/L of arsenic ranges from 3 x 10*5 (on the basis of Taiwanese 
females) to 7 x 10*5 (on the basis of Taiwanese males): or, equivalently, the 
MLE due to 1 ng/kg/day of arsenic intake from water ranges for 1 x 10*3 to 2 
X 10*3. These estimates are about an order of magnitude less than those 
presented in the 1984 HAD. Data from two studies (Cebrian et al., 1983; Fierz, 
1965) were not suitable for dose-response estimation because of lack of 
information on population age structure or lack of a control group. These 


8 


studies were suitable, however, for comparing with the Taiwanese-based risk 
estimates, and were consistent with the dose-response for Taiwan. 

The proportion of nonmelanoma skin cancer cases in the United States 
attributable to inorganic arsenic in the diet, the largest arsenic exposure for 
most Americans, is quite low. Assuming that the dietary intake of inorganic 
arsenic, including the intake from water and beverages, is 0.25 pg/kg/day and 
has been constant for the past 85 to 100 years, the number of skin cancer 
cases per year attributable to inorganic arsenic in food, water, and other 
beverages would be 1,684. This is about 0.34% of the 500,000 cases of 
nonmelanoma skin cancer cases that occur among U.S. Caucasians each 
year. For reasons described in the text, even 0.34% is an overestimate, 
however. 

E. Nutritional Essentiality 

The Technical Panel also reviewed several studies on arsenic as a 
possible essential element in the diet to determine the overall impact of 
arsenic exposure on human health. The information bearing on whether 
arsenic may be an essential element in human nutrition is incomplete. The 
studies of chickens and goats suggested that adverse growth and 
reproductive effects may be attributable to arsenic deficient diets, and that 
arsenic may be required in the diets of these animals. The Technical Panel is 
unaware of comparable studies in human populations. While it is plausible 
that arsenic is a nutritional requirement in animals and a possible requirement 
in humans, additional studies are needed. 

In the absence of definitive information, the likelihood that arsenic is a 
human nutrient must be weighed qualitatively along with risk assessment 
information for carcinogenic effects. There is little information to determine 
the levels of arsenic that would be essential in the human diet, the nature of 
any human effects, or the degree to which current dietary levels are 
adequate. It Is reasonable to assume, however, that there is no sharp 
threshold of essentiality and that a spectrum of effects would occur below 
adequate levels, with the adverse effects of arsenic deficiency increasing in 
severity as exposure is reduced. The risk of cancer would decrease as 
exposure Is reduced, but some risk is assumed to exist at all levels of 
exposure. At low levels of exposure, it is possible that both could occur. 

F. Conclusion 

The Technical Panel concludes that the Taiwan study demonstrates a 
causal association between arsenic ingestion and elevated skin cancer risk. In 
considering the weight of the human evidence of carcinogenicity, the 
possibility of bias, confounding, or chance has been considered. However, 
there is a strong dose-response relationship, and independent studies in 
other countries are concordant in showing the association between arsenic 
ingestion and elevated skin cancer risk. 

Using a multistage model of the skin cancer dose-response data for 
Taiwan, the MLE of lifetime cancer risk for a 70-kg person who consumes 2 
liters of water per day contaminated with 1 pg/L of arsenic ranges from 3 x 
10*5 (on the basis of Taiwanese females) to 7 x 10*5 (on the basis of 
Taiwanese males). The MLE due to 1 pg/kg/day of arsenic intake from water 
ranges from 1 x 10*3 to 2 x 10 * 3 . Although the absence of point mutations 
in genetic tests and certain metabolic information provide some basis for 
considering alternative risk assessment approaches, conservative 
assumptions are consistent with arsenic’s known carcinogenic effects in 


9 


human populations, and an absence of significant information that provides a 
sound basis for an alternative approach. 

An important consideration in evaluating the estimated risks has to do with 
the nature of the carcinogenic response following arsenic exposure. Basal cell 
carcinomas generally do not metastasize and, thus, do not have much 
potential to cause death. They may invade locally, however, and if not 
attended to, can spread to vital centers and lead to morbidity and death. 
Squamous cell carcinomas have some potential to metastasize to contiguous 
structures. Mortality for squamous cell carcinomas is greater than for basal 
cell carcinomas, but is lower than that for the other primary skin tumors, 
malignant melanomas (not associated with arsenic exposure). 

In summary, skin cancers arise in humans following certain exposures to 
arsenical compounds. The tumors are generally superficial, easily diagnosed 
and treated, and are associated with lower mortality than cancers at most 
other sites. Certain internal cancers also appear to be associated with arsenic 
exposure. Lacking definitive information on mechanism of carcinogenic action 
and pharmacokinetics, the Agency has relied on a linear model for 
extrapolation from higher to lower daily exposures to place an upper bound 
on the dose-response estimates. Even in the absence of definitive biological 
information, aspects of the analysis, including lack of genotoxicity and 
pharmacodynamic considerations, suggest that a linear extrapolation may 
overestimate the risks from low-level arsenic exposure. Risks may fall off 
faster than linearly and it is possible that thresholds might exist, but additional 
data are needed to develop this premise. 


10 


III. Hazard Identification and Epidemiologic Studies 
Suitabie for Dose-Response Evaiuation 

A primary issue before the Technical Panel was the validity of the Taiwan 
study (Tseng et al., 1968; Tseng, 1977), which had been used in developing 
the 1984 quantitative risk assessment for skin cancer from ingested arsenic. 
After reviewing the epidemiologic literature, which includes many reports of 
an association between arsenic exposure and skin cancer (see Appendix A), 
the Panel focused on three studies. The Panel found that the Taiwan study 
provided evidence of a causal association between arsenic ingestion and skin 
cancer in humans, resulting in its classification as a Group A human 
carcinogen under EPA’s cancer guidelines (U.S. EPA, 1986). Two other 
studies (Cebrian et al., 1983; Fierz, 1965) showing a skin cancer response 
from arsenic ingestion were used for comparison with predictions from the 
dose-response seen in the Taiwan study. 

A. Preliminary Considerations 

Several of the studies reviewed in this section describe medical conditions 
other than arsenic-induced skin cancer. Before the epidemiologic studies are 
discussed, clarification of these conditions are needed. 

As discussed below, sun-induced skin cancer features skin lesions 
comparable in many respects to those produced by arsenic. However, since 
arsenic-induced skin cancer generally occurs on parts of the body where 
sun-induced skin cancer lesions are rarely found, the former can be 
distinguished from the latter. 

Blackfoot disease or gangrene is another medical condition observed in 
areas of chronic arsenicism. In the Taiwan study, persons with Blackfoot 
disease were more likely to have developed skin cancer than persons who did 
not have Blackfoot disease. Because Blackfoot disease patients in Taiwan had 
a low survival rate and because Blackfoot disease had an earlier median age 
of onset than did skin cancer, it is possible that some potential cancer cases 
among the Blackfoot disease cohort died without being counted in the Tseng 
et al. (1968) prevalence study. 

Finally, excess incidences of some life-threatening malignancies (e.g., 
cancer of the lung, liver, and bladder) are observed in arsenic endemic areas. 
This information has not been fully used in this report because data 
necessary to quantify risk (e.g., dose-response data, information on mortality 
rates, and population age structure) were not available to EPA. Studies and 
case reports that describe an association between arsenic ingestion and 
internal cancer are briefly reviewed in Appendix C. Additional data from the 
studies by Chen et al. (1985, 1986) showing an association between internal 
cancer of several sites and arsenic ingestion have been requested for use in 
dose-response estimation. 


11 


B. Review of Studies 

Three studies identified in the literature review are suitable for quantitative 
evaluation of skin cancer risk. Two are retrospective studies of persons 
exposed to arsenic in drinking water and one is of persons who had been 
treated with a trivalent arsenical medicinal (Fowler’s solution). As stated 
above, none of the studies reviewed for this report provides enough data to 
quantify the internal cancer dose-response due to arsenic ingestion. 

1. Taiwan Study 

Tseng et al. (1968) and Tseng (1977) reported the results of a large 
cross-sectional survey concerning health problems of persons living in an 
area of Taiwan where there were high concentrations of arsenic in the artesian 
well water supply. Use of these wells began in the years 1900 to 1910. The 
wells were reported to be 100 to 280 meters deep, with 80% being between 
120 and 180 meters in depth. The wells were drilled to solve the problem of 
drinking water in the area since the water from shallow wells near the 
seacoast was often salty. Water from the shallow wells was usually free from 
arsenic (<0.001 ppm), although some had a considerably higher 
concentrations (1.097 ppm). In 1956, water containing 0.01 ppm arsenic was 
piped to many places from the reservoir of the Chia-Nan irrigation system. In 
February 1966, a tap water supply was made available to almost the whole 
endemic area in Tainan County. (Personal communication with Drs. Tseng 
and Chien-Jen Chen of the National Taiwan University indicates that the 
artesian wells are still used [to some extent] during dry periods.) The arsenic 
level in the wells varied somewhat over time but appeared to be highest 
during Taiwan’s rainy season. In the early 1960s the concentrations of arsenic 
in the different wells ranged from 0.01 to 1.82 ppm. 

By 1965, physical examinations had been performed on a total population 
of 40,421 in 37 villages. The entire population in all villages in the study area 
numbered 103,154. The period of the survey was not specified by the authors 
in their publication, but personal communication indicates that the survey 
period was about 2 years. Investigators gave special attention to 
hyperpigmentation, hyperkeratosis, and skin cancer. A control population of 
7,500 persons, with age distribution similar to that of the study population but 
from areas in which arsenic was not endemic in the drinking water supply, 
was examined in the same way as the arsenic-exposed persons. The 
arsenic in the drinking water of this comparison population ranged from non- 
detectable (detection limit not specified) to 0.017 mg/L. Males in the study 
and control populations were engaged in similar occupations (fishing, farming, 
and salt production). Four hundred and twenty-eight cases of skin cancer 
(10.6/1,000) were found in the study population. Of these, 153 were reported 
to be histologically confirmed. There were no cases in persons less than 20 
years old and the prevalence increased markedly with age, except for women 
over 70. The male-to-female skin cancer prevalence ratio was 2.9:1. There 
was a clear-cut increase in prevalence with exposure. 

Of the 428 people with clinically diagnosed skin cancer, 72% also had 
hyperkeratosis2 and 90% had hyperpigmentation. Seventy-four percent of 


2These are assumed to be benign hyperkeratoses as opposed to the 
Type"B”hyperkeratoses described by Yeh (1973) as intraepidermal carcinomas and 
which were counted as skin cancer. 


12 



the malignant lesions were on areas not exposed to the sun. Ninety-nine 
percent of the people with skin cancers had multiple skin cancers. Yeh (1973) 
studied 303 of the 428 skin lesions originally reported by Tseng et al. (1968) 
histologically: 57 were squamous cell carcinomas: 45 were basal cell 
carcinomas (28 deep, 17 superficial): 176 were intraepidermal carcinomas (23 
Type B keratoses, 153 Bowen’s disease): and 25 were combined forms. 

The prevalence rate for Blackfoot disease was 8.9 per 1,000 in the study 
population. Prevalence rates for keratosis and hyperpigmentation in the study 
population were 183.5 and 71 per 1,000, respectively. The youngest patient 
with hyperpigmentation was 3 years old, the youngest with keratosis was 4, 
and the youngest with skin cancer was 24. 

No cases of skin cancer, Blackfoot disease, hyperkeratosis, or hyper¬ 
pigmentation were found in the control population of 7,500. One could argue 
that this suggests a potential bias on the part of the examiners since they 
were not "blinded" as to whether the persons being examined were from the 
arsenic area or not. Thus, they might have made a greater effort to ascertain 
cases in the study population than in the comparison population. All of the 
study subjects were examined by the same physicians according to a 
common protocol however, the disease was relatively easy to diagnose 
differentially (Chen et al., 1986). Furthermore, over 70% of the skin cancer in 
the exposed population were histopathologically confirmed. Lastly, at least 
with regard to skin cancer, the fact that no cases were found in the 
comparison population is not inconceivable, since the expected number of 
skin cancer cases in the control population of 7,500 persons (using the skin 
cancer rate for Singapore Chinese from 1968 through 1977) is a little less 
than 3. Using this as the expected prevalence, the probability of observing no 
cancer cases is 0.07. 

Subsequent analysis of the drinking water revealed substances other than 
arsenic including bacteria and ergot alkaloids (Andelman and Barnett, 1983). 
Neither of these two substances has been previously associated with skin 
cancer, and it seems unlikely that these two substances could be considered 
confounders. Also, as outlined in Appendix A, a multitude of studies have 
demonstrated an association between arsenic ingestion and skin cancer. It 
seems unlikely that the same confounders that might have been present in 
the Tseng et al. (1968) study would have been present in the other studies as 
well. Chen noted, however, that the presence of substances in the well water 
other than arsenic, although not confounding, might have produced a 
synergistic effect (Chen, 1987). 

2 . Mexican Study 

Cebrian et al. (1983) and Albores et al. (1979) reported the results of a 
prevalence study of individuals living in two towns in the Region Lagunera 
section of Mexico (the exposed town of El Salvador de Arriba and the control 
town of San Jose del Vinedo Diego). The two towns are 37 km apart, are very 
similar with regard to economic and atmospheric conditions, and have similar 
age and sex distributions except for the over 60 age groups where the 
proportion of individuals was slightly greater in the control town. The only 
apparent important difference between them is in the level of exposure to 
arsenic in water. Monitoring from August 1975 to May 1978 showed the 
average arsenic level to be 0.411 ± 0.114 mg/L (20 samples) in El Salvador 
de Arriba and 0.005 ± 0.007 mg/L (18 samples) in San Jose del Vinedo 
Diego (in each case about 70% pentavalent, 30% trivalent), varying somewhat 
over time. Historical exposure levels are not known: organoarsenical pesticide 


13 


runoff into the water supply may have been an additional source of arsenic (in 
both towns) before 1945. 

Dr. Mariano Cebrian (1987), the primary investigator, indicates that there 
was one well per community, and that the well was located in the center of 
each of the respective towns. Each well had been drilled to a depth of about 
70 to 100 meters. The water was then distributed to approximately ten holding 
tanks from which the residents drew their water. In addition to arsenic, fluoride 
was also reported to be present in the water supply of the exposed town. 
Arsenic concentrations in the water supply were reported to correlate with 
fluoride concentrations in the Region Lagunera (Cebrian, 1987). Chemical 
analysis was not done for any substances other than fluoride and arsenic. 

Every third household in the two towns was sampled, and each member 
present in the household was examined. Data on exposure sources and 
number of years of exposure were obtained by means of questionnaires from 
296 people from El Salvador de Arriba and 318 people from San Jose del 
Vinedo Diego. Physical examinations were performed on each resident in the 
sampled households to assess hyperpigmentation, hypopigmentation, papular 
and palmoplantar keratoses, and ulcerative lesions. 

A 3.6-fold greater risk of ulcerative lesions, compatible with a clinical 
diagnosis of epidermoid or basal cell carcinoma, was reported in the exposed 
population as compared to the controls. This report was based on four cases 
(which were not histologically confirmed) from El Salvador de Arriba 
(prevalence rate of 14/1,000) and no cases from San Jose del Vinedo Diego. 
In contrast to the observation of Tseng et al. (1968), there was no sex 
difference in the distribution of lesions. The shortest latency period for skin 
cancer (one case) was 38 years which was also the age of the individual (age 
was similar to residence in 75% of the patients.) Of the remaining three 
cases, two were in the 50 to 59 age group and one was in the > 60 age 
group. Hypopigmentation was discovered in 17.6% of the exposed persons, 
hyperpigmentation in 12.2%, and palmoplantar keratoses in 11.2%. No 
biopsies were taken. No other skin lesions were reported for the exposed 
town; however, peripheral vascular disease such as that reported in Taiwan 
(i.e., Blackfoot disease) has also been reported in the arsenic endemic area of 
Region Lagunera in Mexico (Salcedo et al., 1984).3 The shortest latency for 
hypopigmentation was estimated to be 8 years, for hyperpigmentation and 
palmoplantar keratosis 12 years, and for papular keratosis 25 years. Based on 
average drinking water arsenic concentrations of 0.41 mg/L, Cebrian 
calculated the following minimum total ingested doses for the development of 
cutaneous toxicity: hypopigmentation, 2 g; hyperpigmentation, 3 g; keratoses, 
3 g; invasive carcinoma, 2 g. The minimum detection time and the lowest 
cumulative dose may have been overestimated, since it is not known at what 
age the lesions may have first become clinically apparent. A few classical 
arsenic-induced skin lesions were identified in the control population: 
hypopigmentation in 2.2%, hyperpigmentation in 1.9%, and palmoplantar 
keratosis in 0.3% (Cebrian et al.. 1983). The authors speculated that the 
occurrence of lesions in the control town may have resulted from ingestion of 
foodstuffs produced in the same region and contaminated with arsenic. 


3The reported Blackfoot disease in Mexico and Taiwan is consistent with a report 
(Borgono and Greiber, 1972) of Blackfoot disease in an area of Chile where there is 
arsenic contamination of the water supply. 


14 



In contrast to the situation in Taiwan, the Mexican population had limited 
water supplies, thus enabling more accurate estimates of exposure. This 
study also presents potential problems, however. The study may be biased 

since the examiners knew who were exposed and who were not. The 

possibility of preferential diagnosis may not have been as great in this study 

as it was in the Taiwan study, since cutaneous signs other than ulcerative 

lesions were observed in the control population. Also, there was no estimate 
of non-response (i.e., the number of individuals not present at the time of the 
interview and/or examination is not reported). 

3 . German Study 

Fierz (1965) reported on a retrospective study of patients treated with a 1:1 
dilution of Fowler’s solution containing 3.8 g arsenic/L. An accurate 
assessment of the total arsenic intake was available from patient records. A 
total of 1,450 patients were identified as having received arsenic treatment 6 
to 26 years previously. Invitations for a free medical examination were mailed 
to them. Two hundred sixty-two persons presented themselves for 
examination; 100 patients refused to participate, and 280 could not be 
located. The status of the other 808 persons to whom invitations had been 
mailed was not reported. Of the 262 examined, 64 had been treated with 
Fowler’s solution for psoriasis, 62 for neurodermatitis, 72 for chronic eczema, 
and 64 for other disease. Twenty-one cases of skin cancer were found, 
comprising 8% of the subjects examined. Multiple carcinomas were found in 
13 of the 21 patients; 10 of these were multiple basal cell carcinomas, 
described as polycyclic, sharply bounded erythemas with slight infiltration. 
Single basal cell carcinoma, squamous cell carcinoma, and Bowen’s disease 
were less frequently encountered. Of the 21 patients with carcinomas, 16 
showed distinctly developed "arsenic warts" on the palms and soles, 
simultaneously with skin tumors. The author estimated the minimum and 
mean latency period for carcinomas to be 6 and 14 years, respectively. 
However, the latency period did not appear to be correlated with dose. 

Hyperkeratosis was the most frequent sign of arsenic toxicity, occurring in 
106 of 262 (40.4%) of the patients. In patients who had received the 
equivalent of 3 g of arsenic as the diluted Fowler’s solution, the incidence of 
hyperkeratosis was 50%. The minimal latency period for hyperkeratosis was 
reported to be 2.5 years; the mean latency period was not reported. Melanotic 
hyperpigmentation was found in only 5 of 262 persons (2%); however, 3 
persons reported that they had looked "stained" shortly after taking arsenic, 
but that this condition had regressed over the years. The incidence rates of 
both skin cancer and hyperkeratosis increased with dose. The size of the 
hyperkeratoses also increased with dose. The author also found that the 
original diagnosis (psoriasis, neurodermatitis, chronic eczema, or acne) did 
not affect the development of skin cancer when dose was controlled for. 

One problem with this study is that a significant proportion of the exposed 
population did not participate in the study. Three hundred and eighty persons 
of a total of 1,450 (59%) refused to participate or could not be contacted. It is 
not known what became of 808 other persons to whom invitations had been 
mailed. The author classified the 262 who did present themselves for 
examination into three groups: those satisfied with the results of the arsenic 
treatment and wishing to express thanks; those in whom side effects were 
occurring (e.g., skin cancer, hyperkeratosis, etc.); and those who were still 
suffering from the initial disease and who were eager to get consultation. This 
description makes apparent the possibility of selection bias. Another problem 
is the lack of a control group. 


15 


C. Summary 

The Taiwan (Tseng et al., 1968; Tseng, 1977), Mexican (Cebrian et al., 
1983), and German (Fierz, 1965) studies have been discussed in detail 
because they have been used as part of the dose-response assessment in 
Part V. Additional reports of the association of arsenic ingestion and cancer 
risk are found in Appendix A. (Reports of an association between ingested 
arsenic and cancers of internal organs are discussed in Appendix C.) 

Strengths of the Taiwan study include; (1) the study and comparison 
populations were large enough'(40,421 and 7,500 respectively) to provide 
reliable estimates of the skin cancer prevalence rates, (2) a statistically 
significant elevation in the skin cancer prevalence among the exposed 
population over that of the comparison population was observed many years 
after first exposure, (3) there was a pronounced skin cancer response by 
arsenic exposure level, (4) the exposed and comparison populations were 
similar in socioeconomic status and occupation with the only apparent 
difference between the two populations being that of arsenic exposure, and 
(5) over 70% of the observed skin cancer cases were pathologically 
confirmed. 

Important uncertainties of the Taiwan study include: (1) chemicals other 
than arsenic in drinking water which may have confounded the observed 
association between skin cancer and arsenic ingestion, and (2) the lack of 
blinding of the examiners which may have led to a differential degree of 
ascertainment between the exposed and comparison populations. Another 
uncertainty relates to the possibility that diet may have modified the 
response. 

The Mexican study found the prevalence of skin cancer increased in a 
population exposed to arsenic via drinking water versus a comparison 
population, but the sample sizes of the exposed and comparison groups (296 
and 318, respectively) were much smaller than the Taiwan study. Futhermore, 
there were only four cases of skin cancer among the exposed. The German 
study of patients who ingested arsenical medicinals reported a skin cancer 
dose-response by the amount of arsenic ingested, but there was no 
comparison group and many of the exposed population did not participate in 
the study. Both studies (Mexican and German), despite their limitations, were 
considered useful for quantitative comparison with the results from Taiwan. 
(See Part V. Dose-Response Estimate for Arsenic Ingestion) 

In reviewing the weight of the human evidence of carcinogenicity, the 
possibility of bias, confounding or chance has been considered. However, 
there is a strong dose-response relationship, and independent studies in 
other countries are concordant in showing the association between arsenic 
ingestion and elevated skin cancer risk. 

Considering the above, arsenic is classified as a Group A human 
carcinogen (U.S. EPA, 1986), for which there is sufficient evidence from 
epidemiologic studies to support a causal association between exposure to 
this agent and cancer. 


» V-i 


16 


IV. Selected Elements of Hazard Identification 


This part summarizes biological information relating to the skin cancer 
dose-response for ingested arsenic. Section A reviews certain pathologic 
features of skin lesions associated with arsenic exposure and comments on 
their significance. Section B summarizes the genotoxicity of arsenic and 
discusses its role in the cancer dose-response assessment. Section C 
highlights relevant metabolic information. 

A. Pathologic Characteristics and Significance of Arsenic- 
Induced Skin Lesions^ 

Several aspects of arsenical skin lesions are briefly reviewed here to 
provide a background for distinguishing the nature and relative health impact 
of the skin lesions upon which the dose-response assessment is based. The 
discussion also shows that certain lesions may serve as biological markers of 
early arsenic exposure. Subsection 1 describes the pathology of the various 
skin lesions; subsection 2 discusses the interrelationship between these 
lesions with respect to progression from a preneoplastic stage to a malignant 
neoplasm; and subsection 3 examines the case-fatality rate of basal cell and 
squamous cell carcinoma. 

1. Description and Malignant Potential of Skin Lesions 

Several different skin lesions that are described in various reports of 
arsenic-exposed humans are discussed. Yeh et al. (1968), in his study of 
patients with chronic arsenicism, provides the most complete description of 
the various skin lesions, particularly hyperpigmentation, hyperkeratosis, and 
skin cancer. Skin cancer, as defined by Yeh et al. (1968), includes 
intraepidermal carcinomas (Type B keratosis and Bowen’s disease), basal cell 
carcinomas, invasive squamous cell carcinomas, and "combined lesions." 

Hyperpigmentation is a pathologic hallmark of chronic arsenic exposure 
and may occur anywhere on the body, typically as dark brown patches 
showing scattered pale spots. Hyperpigmentation is not considered to be a 
malignant neoplasm or a precursor to malignancy. Although it may occur 
together with hyperkeratosis, hyperpigmentation does not appear to be 
directly related to hyperkeratosis (i.e., they are not different stages in the 
evolution of a single type of lesion, but, rather, are of different cellular lineage 
and are related only because of their common cause). 


^An expert pathologist. Dr. D. S. Strayer of the University of Texas Medical School at 
Houston, was asked by the ERA Risk Assessment Forum to review the literature on 
arsenical skin pathology. Subsections 1 and 2 of this section are based on that review. 


17 



Yeh et al. (1968) and Yeh (1973) reported that arsenical hyperkeratosis 
occurs most frequently on the palms of the hands and soles of the feet; 
however, hyperkeratosis may occur at other sites. Hyperkeratoses usually 
appear as small corn-like elevations, 0.4 to 1 cm in diameter. Yeh (1973) 
concluded that in the majority of cases, arsenical keratoses showed very little 
cellular atypia and are morphologically benign. Thus, Yeh (1973) divided the 
arsenical keratoses in the Tseng studyS (1977; Tseng et al., 1968) into two 
groups: Type A, which included mildly atypical cells, and a malignant Type B, 
which included cells with more marked atypia. Authors of some other studies 
do not make this distinction. Yeh et al. (1968) stated that keratotic lesions of 
chronic arsenicism, although histopathologically similar, were distinguishable 
from Bowen’s disease. Some pathologists, however, state that arsenical 
keratoses are difficult to distinguish from Bowen’s disease: some considered 
them one and the same (Hugo and Conway, 1967). As discussed later. Type 
B keratoses may evolve into invasive squamous cell carcinoma. 

Bowen’s disease, an in situ squamous cell carcinoma, represents a 
continuation of the dysmaturation processes observed in Type B keratoses. 
These lesions may become invasive, but the frequency is not known. These 
lesions are sharply demarcated round or irregular plaques that may vary in 
size from I mm to more than 10 cm, and tend to enlarge progressively. 
Arsenic-associated Bowen’s disease is usually multifocal and randomly 
distributed and the lesions tend to arise on the trunk more often than do 
arsenical hyperkeratoses. 

Arsenical basal cell carcinomas most frequently arise from normal tissue, 
are almost always multiple, and frequently occur on the trunk. The superficial 
spreading lesions are red, scaly, and atrophic and frequently indistinguishable 
from Bowen’s disease by clinical examination. 

Arsenical invasive squamous cell carcinomas (referred to as epidermoid 
carcinomas in Yeh (1973) and Yeh et al. (1968) arise from normal tissue or 
within preexisting hyperkeratoses or Bowen’s disease. Persistent fissuring, 
erosion, ulceration, and induration are key clinical features. Although 
arsenic-associated squamous cell carcinomas do not differ 
histopathologically from sun-induced squamous cell carcinomas, they can 
be distinguished by their common occurrence on the extremities (especially 
palms and soles) and trunk; sun-induced squamous cell carcinomas appear 
primarily on sun-exposed areas (i.e., the head and neck). 

Finally, several reports describe "combined lesions" that were considered 
attributable to arsenic that include both basal cell carcinomas and Bowen’s 
disease (Yeh et al., 1968), or mixed squamous cell carcinomas and basal cell 
carcinomas (Sommers and McManus, 1953). Whether these represent true 
mixed lesions or coalescence of two separate lesions has been debated by 
Sanderson (1976). He argues that because arsenical skin cancer includes 
multiple foci, separate foci of the same type of neoplasia or two different 
types of adjacent neoplasias may eventually collide and blend together, 
producing a "combined lesion." 

In summary, distinguishing characteristics of lesions of arsenical skin 
cancer, include multiplicity and distribution on unexposed parts of the body 
(e.g., palms of the hands, soles of the feet, other parts of the extremities, and 


SThe Tseng study is the epidemiologic study that forms the basis of the cancer risk 
estimate associated with ingested arsenic (see Sections B and C). 


18 



trunk). Sun-induced basal cell carcinomas do not metastasize and the 
metastatic potential of squamous cell carcinomas is low; whether this is also 
true for arsenical skin cancer is unknown. As discussed in subsection 3 of this 
section, there is some basis for speculating that arsenical skin cancer may 
have a higher metastatic potential than sun-induced skin cancer. 

2 . Progression of Skin Lesions 

The interrelationship between the various lesions of chronic arsenicism 
was examined to further characterize lesions that would be used to develop 
the dose-response assessment. For example, the frequency of 
transformation from the benign lesions to the malignant lesions would better 
characterize the proportion of benign lesions that might be factored into the 
dose-response assessment.6 Progression of lesions was also examined to 
provide a qualitative discussion of carcinogenic mechanisms that might 
indicate the suitability of a particular extrapolation model. There was not 
enough information on progression of lesions in arsenic-exposed humans for 
the Technical Panel to develop a mechanistic model. As suggested in section 
C of this part, future studies may provide useful information. 

The development of arsenical keratosis and Bowen’s disease into invasive 
squamous cell carcinoma is documented in certain instances (see Table 1). 
Note in Table 1 that Yeh et al. (1968) also cited one basal cell carcinoma that 
arose from keratotic lesions. Whether the keratoses referred to in the table 
are of type A or B as described by Yeh et al. (1968) is unknown. The 
frequency of malignant transformation, however, is difficult to determine 
because many case reports of arsenical skin cancer do not specify the pre¬ 
existing condition of the skin. Moreover, analysis of some reports is 
complicated by lack of histopathologic examination or by uncertain 
terminology. 

Invasive squamous cell carcinoma, basal cell carcinoma, and Bowen’s 
disease ("//? situ" squamous cell carcinoma) were used as end points for the 
cancer dose-response assessment. Type B keratoses were also included 
since Yeh et al. (1968) had classified them as an intraepidermal carcinoma 
which, by inference, were malignant. Although the Type A keratoses were 
classified by Yeh et al. (1968) as benign, they may have malignant potential. 
Type A keratoses were not used in the dose-response assessment, 
however, because there was a lack of information on the distribution of Type 
A keratotic lesions by age and dose, and the malignant potential was not 
clearly established. Hyperpigmentation was not included in the dose- 
response assessment since hyperpigmentation is not a malignant condition, 
and it does not appear to be a pre-malignant stage in nonmelanoma skin 
cancer. Both of these lesions are indicators of arsenic exposure, and can 
serve as biological markers. 

3 . Case-Fatality Rate of Arsenic-Induced Skin Cancer 

The Technical Panel examined the public health impacts of arsenic- 
induced skin cancer for U.S. residents by using case-fatality rates for skin 


6The EPA cancer guidelines (U.S. EPA, 1986) state that “Benign tumors should 
generally be combined with malignant tumors for risk estimates unless the benign 
tumors are not considered to have the potential to progress to the associated 
malignancies of the same histogenic origin.” 


19 



Table 1. Invasive Malignant Transformation of In Situ Arsenic-Induced Skin Lesions 


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20 







cancer, data that give the cumulative incidence of death among people who 
develop this condition. However, since data on case-fatality rates for 
arsenic-induced skin cancer in the United States are not available, the 
Technical Panel drew on two sources to estimate the case-fatality rate of 
arsenic-induced skin cancer in the United States. The most direct 
information upon which to estimate a case-fatality rate from arsenic- 
induced skin cancer in the United States would be derived from U.S. 
arsenic-exposed populations. However, the only case-fatality rate reported 
for an arsenic-exposed population is that of Yeh (1973), who observed a 5- 
year case-fatality rate of 14.7% for patients with arsenic-induced skin 
cancer in Taiwan. 

Differences in medical care between the Taiwanese and U.S. populations 
may lead to different case-fatality rates in the two countries. Thus, 
approximations of the case-fatality rates for basal and squamous cell 
carcinoma for both males and females in Caucasian U.S. populations were 
derived from aggregate data on nonmelanoma skin cancer and are presented 
in Table 2; these data primarily reflect sun-induced skin cancer. Table 2 
shows that nonmelanoma skin cancer, which is the most common malignant 
neoplasm among Caucasians in the United States (Scotto and Fraumeni, 
1982), is rarely fatal; less than 2% of all nonmelanoma skin cancer cases die 
from the disease. These low case-fatality rates probably reflect the ease of 
diagnosis and effectiveness of treatment. Case-fatality rates could not be 
calculated for nonwhites due to lack of data on nonmelanoma skin cancer 
incidence rates. 

In conclusion, the estimated case-fatality rate attributable to arsenic- 
induced skin cancer ranges between <1% (U.S. populations) to 14.7% 
(Taiwanese populations). There is currently not enough information to 
determine whether the case-fatality rates in Table 2 or that based on the Yeh 
data realistically describe the probability of death in the United States due to 
arsenic-induced skin cancer. The higher case-fatality rate of 14.7% 
reported by Yeh may reflect differences in medical treatment between Taiwan 
and the United States or may reflect differences in disease aggressiveness 
for arsenic exposure relative to sun exposure resulting from several factors. 
For example, arsenical nonmelanoma skin cancer often appears as multiple 
lesions on the body, presenting a higher probability of metastasis. Arsenic- 
induced skin cancer has a higher squamous to basal cell ratio than does 
nonmelanoma skin cancer in the United States, the majority of which, as 
stated above, is believed to be sun-induced, and squamous cell carcinoma 
has a higher probability of metastasis than does basal cell. Finally, arsenic- 
induced skin cancer tends to occur on the trunk and extremities, areas that 
are not generally sun-exposed. Lesions in these areas may not be as readily 
detected by the patient or physician, thus increasing the probability of not 
diagnosing the disease until a more advanced stage. 

B. Genotoxicity 7 
1. Introduction 

Various inorganic compounds of arsenic have been tested for mutagenicity 
in a variety of test systems ranging in complexity from bacteria to peripheral 


7With permission of the authors, this discussion is adapted from a review article prepared 
by Jacobson-Kram and Montalbano (1985) and the U.S. ERA Health Assessment 
Document for Inorganic Arsenic (U.S. ERA, 1984a). 


21 



Table 2. Estimated Case-Fatality Rates for Nonmeianoma Skin Cancer by 
Cell Type^ 

Estimated 


Race-sex 

group 

Cell type 

Incidence 

rate/ 

100,0003 

Mortality 

rate/ 

100,000b 

Estimated 

case-fatality 

ratec 

White male 

Squamous cell 

65.5 

0.8 

1.2% 

White male 

Basal cell 

202.1 

0.2 

<0.1% 

White female 

Squamous cell - 

21.8 

0.3 

1.4% 

White female 

Basal cell 

115.8 

• 0.08 

<0.1% 


aBased on annual incidence rates, age-adjusted to the 1970 U.S. population (Scotto 
and Fraumeni, 1982). 

bRace-specific nonmelanoma skin cancer mortality rates were obtained from Riggan 
et al. (1983) and are age-adjusted to the 1970 U.S. population. An assumption, 
based on Scotto and Fraumeni (1982) was made for this analysis that squamous cell 
carcinoma deaths accounted for 80% of the race-sex specific age-adjusted 
mortality rate. 

^Estimated case-fatality rate = Estimated mortality rate/incidence rate (MacMahon 
and Pugh, 1970). The following three assumptions were made: (1) incidence of 
nonmelanoma skin cancer remains stable for a period corresponding to the longest 
duration of the disease in the individual; (2) the distribution of disease duration 
remains stable; and (3) the proportion of patients with various outcomes (death or 
recovery) remains stable. All assumptions are believed to be met since disease 
duration is relatively short and survival is good. 

lymphocytes of exposed human beings. Although much of the data presents 
many questions, the weight of evidence leads to five conclusions: 

(1) Arsenic is either inactive or extremely weak for the induction of gene 
mutations in vitro. 

(2) Arsenic is clastogenic and induces sister chromatid exchanges (SCE) in a 
variety of cell types, including human cells, in vitro] trivalent arsenic is 
approximately an order of magnitude more potent than pentavalent 
arsenic. 

(3) Arsenic does not appear to induce chromosome aberrations in vivo in 
experimental animals. 

(4) Several studies suggest that human beings exposed to arsenic 
demonstrate higher frequencies of SCE and chromosomal aberrations in 
peripheral lymphocytes. 

(5) Arsenic may affect DNA by the inhibition of DNA repair processes or by 
its occasional substitution for phosphorous in the DNA backbone. 

Several reviews on the mutagenicity of arsenic are available (Jacobson- 
Kram and Montalbano, 1985; Flessel, 1978; National Academy of Sciences, 
1977; Leonard and Lauwerys, 1980; World Health Organization, 1981). 

2. Possible Mechanisms of Genotoxicity 

Arsenic is unusual in several respects. First, unlike the majority of 
clastogenic agents, arsenic does not appear to directly damage DNA except, 
perhaps, at highly cytotoxic doses. Rather, it seems to have its effect through 
some interference with DNA synthesis. This contention is supported by 
observations that arsenic induces chromosomal aberrations and SCE only 
when it is present during DNA replication. Incubation and removal of arsenic 
before DNA synthesis has no effect (Nordenson et al., 1981; Crossen, 1983). 


22 




Second, arsenic is unusual in that it induces chromosomal aberrations and 
SCE while it fails to induce gene mutations. In this regard it is like benzene, 
another unusual carcinogen (Dean, 1978). Although capable of producing 
chromosome aberrations as well as gene mutations, x-irradiation is much 
more potent for the former end point. There is a small possibility, however, 
that the discrepancy for arsenic is an artifact. Protocols for gene mutation 
assays generally involve cellular incubation with the test agent for relatively 
short time periods (2-3 hr), while protocols for aberrations often involve the 
presence of the test agent for one or two entire cell cycles (12-48 hr). Thus, 
in the latter protocol, arsenic would be present for at least an entire S-phase 
for all cells, whereas, when tested for gene mutations, arsenic would be 
present for only a small fraction of the S-phase in approximately one-third 
to one-half of the cells. Since the evidence available suggests that arsenic 
has its effect only during DNA replication, this may account for the 
discrepancy. 

Arsenic has long been known to be a sulfhydryl reagent capable of 
inhibiting a number of thiol-dependent enzyme systems, trivalent forms 
being much more potent than pentavalent forms (Leonard and Lauwerys, 
1980). Thus, one possible mechanism of action for arsenic would be the 
inhibition of DNA repair enzymes. The work of Rossman in bacteria (1981) 
and Jung et al. (1969) in human cells in vitro lend support to this hypothesis. 
Also the observations of Sram (1976) on the interactions of arsenic with 
tris(1-aziridinyl) phosphine sulphide (TEPA) for the induction of 
chromosomal aberrations and dominant lethals support such a contention. 
The potencies of trivalent and pentavalent arsenicals as sulfhydryl reagents 
are similar to their potencies as clastogens and SCE-inducing agents. 
Observations that counter this hypothesis are the reports by Rossman that 
arsenic has no effect on the frequency of UV-induced mutations in 
mammalian cells in vitro and that arsenic does not affect the frequency of 
EMS-induced aberrations in vivo (Poma et al., 1981). 

Another possible mechanism for the action of arsenic may be through its 
occasional incorporation into the DNA backbone in place of phosphorous. 
There are several lines of evidence to support this mechanism. First, for this 
to occur, arsenic would have to be present during DNA synthesis and would 
have no effect on nondividing cells. Second, such a mechanism could explain 
why arsenic is clastogenic (such a bond would be weaker than the normal 
phosphodiester bond) but does not induce gene mutation. Third, arsenic has 
been shown to cause strand breaks in DNA (Fornace and Little, 1979). Also, 
x-irradiation, a potent clastogen and poor inducer of gene mutations, 
predominantly causes strand breaks as its major DNA lesion. An argument 
against such a mechanism is the observation that the trivalent forms are more 
potent than pentavalent forms, while pentavalent arsenic should be more 
likely to substitute for phosphorous in DNA. Furthermore, arsenic would have 
to be capable of being phosphorylated. 

3. The Use of Arsenic Genotoxicity Data in the Evaluation of 
Carcinogenic Risk 

Genotoxicity at low doses is an important indicator of irreversible change in 
genetic function. Such changes are a critical feature of many postulated 
mechanisms for chemical carcinogenesis and the basis for ascribing low- 
dose linearity to carcinogenic processes. Although the lack of genotoxic 
response does not preclude linearity at low doses, it is potentially important 
as a consideration in selecting a model for extrapolation of carcinogenic risk. 


23 


The in vitro dose-response function for the induction of chromosomal 
aberrations by both trivalent and pentavalent arsenic is linear. It is important 
to note, however, that most chromosomal aberrations scored in a standard 
cytogenetics assay, such as that used in the evaluation of arsenic, are lethal 
events. The cells scored in these assays carry lesions that do not permit 
them to survive more than one or two additional cell cycles after damage and 
are, therefore, genetically of no consequence. 

Agents that are capable of breaking chromosomes are also capable of 
causing stable chromosome rearrangements, such as translocations or 
inversions. To induce such a rearrangement, at least two chromosomes per 
cell must be damaged (or one chromosome damaged twice). Based on 
simple target theory, one would expect a nonlinear dose-response 
relationship for the induction of rearrangements at low doses. In this case, 
there are two targets per cell, both of which must be hit in order to bring 
about a rearrangement. At low doses, both targets must be hit in order to 
bring about a rearrangement, and the possibility of hitting both targets in a 
single cell is small, but finite. Further, if as discussed above, arsenic acts by 
interfering with DNA synthesis and repair processes, rather than by causing 
mutations, the need for two events is compounded by the need for arsenic 
also to produce toxic effects on DNA synthesizing enzymes. With increasing 
doses, many cells will contain a single hit and the dose effect curve becomes 
linear. 

The size of any apparent "practical threshold" will be determined by the 
"size" of the target; i.e., if a high percentage of arsenic molecules interact 
with chromosomes to cause breaks, the targets are large, and the observed 
threshold is small. Although these observations suggest the existence of a 
"practical threshold," there is a measurable "spontaneous" frequency of 
chromosomal breaks. Because a cell may already carry one break, the 
induction of the second break (and the resulting rearrangement) would be a 
single hit phenomenon. Indeed, the induction of dicentrics (a two-hit 
chromosomal rearrangement) is linear for ionizing radiation even at very low 
doses. Clearly, these arguments do not support the existence of a threshold, 
a dose level below which aberrations would not occur. However, the 
possibility of a nonlinear dose-response relationship at low doses should be 
recognized. 

How chromosomal rearrangements would influence the carcinogenic 
process is only speculative at this time. Although there are examples of 
oncogene activation associated with cancers in humans and experimental 
systems, arsenic-induced chromosomal changes have not been observed in 
vivo, and no data are yet available for arsenic-induced cancers in regard to 
oncogene activation. While lack of mutagenic activity may argue against the 
notion that single arsenic-cell interactions may start a process leading to 
malignancy, gene mutation may not be the only factor leading to low-dose 
linear dose-response relationships. 

C. Metabolism and Distribution (See Appendix E) 

Inorganic arsenic is a potent poison resulting in adverse effects following 
acute exposure. Acute toxicity studies indicate that inorganic compounds are 
more potent than organic forms, and valence state-3 inorganic arsenicals are 
more toxic than valence state-5 compounds across a number of species. 
Since the mammalian body can interconvert inorganic arsenic species and 
can methylate valence state-3 compounds, it appears that methylation is a 


24 


means of detoxifying inorganic forms. As more methyl groups are added, the 
compounds become less and less acutely toxic. 

Although there are many data gaps in our understanding of the body’s 
handling of arsenic, great strides have been made in recent years in the 
ability to speciate among valence states of arsenic. The picture that unfolds is 
as follows. Inorganic arsenic ( + 5) can be interconverted in the blood with 
( + 3) - inorganic forms, and the latter can be singularly methylated to form 
mono-methyl arsenic (MMA); these are enzymatic and nonenzymatic 
processes. It appears that arsenite, but not arsenate can enter liver cells (at 
least in vitro) where a second methyl group can be added: MMA becomes 
dimethyl arsenic (DMA) via a rate-limiting enzymatic process. 

Under low-level exposures to arsenic, there seems to be a balance 
between the amount entering the body and the amount being excreted. Most 
absorbed arsenic is lost from the body in the urine as inorganic arsenite, 
MMA, DMA, and other, yet uncharacterized, organic forms. A small amount of 
arsenic is lost by desquamation of the skin. 

With increasing arsenic intake there is suggestive evidence that there is 
some maximal amount the body can readily handle. An early study (Valentine 
et al., 1979) noted that ingested arsenic in blood did not change as a function 
of dose until water concentrations exceeded about 100 pg/L. Buchet et al. 
(1981, 1982) suggest that the body’s ability to form DMA seems hampered at 
exposures in excess of about 500 pg/day, without affecting the excretion of 
inorganic arsenic or MMA in the urine. If this is the case, then total urinary 
excretion of arsenic may be compromised at high doses leading to increased 
tissue levels. 

Given the predilection of arsenic for tissues with high sulfhydryl groups, 
like skin, it seems plausible that high arsenic loads may be associated with 
increased deposition in the skin. The nature of the binding of arsenic to the 
skin is unknown at this time; however, radioisotopically labeled inorganic 
arsenic is retained for longer times than are organic arsenicals. In addition, 
more drastic chemical treatments are required to remove arsenic from the 
skin following administration of inorganic than organic arsenic. These pieces 
of evidence suggest that the binding in the skin after inorganic arsenical 
exposures is more tenacious and more stable than that following exposure to 
organic compounds. Although these findings are interesting, the way that they 
may influence the carcinogenic process, either qualitatively or quantitatively, 
has not been ascertained. 

Another finding is that the methylating capacity of the body may change as 
a function of exposure, such that maximal levels of excretion of methylated 
arsenicals are reached after weeks of exposure to the compound. In a like 
manner, the ability to excrete methylated arsenicals seems to be lost as a 
function of time after removal of arsenical exposure. Thus, with alternating 
arsenical intake, individuals may go through periods of efficient metabolism 
and excretion as well as a tendency to accumulate body stores of arsenic. 

It is possible that differences in diet between the United States and Taiwan 
may have modified the carcinogenic effects of arsenic. The Taiwan diet was 
reported to be "low in protein and fat; carbohydrates, rice, and sweet potatoes 
constitute the main part of the diet " (Tseng et al., 1968). It is possible that 
the reduced protein in the Taiwan diet may compromise the body’s ability to 
methylate and excrete arsenic. Experiments in animals indicate that under 
methioninedeficient conditions, the body’s ability to methylate (Shivapurkar 
and Poirier, 1983) and excrete arsenic is compromised (Marafante and 
Vahter, 1986). Some studies in South America where diets seem to be protein 
adequate, however, indicate that skin cancer still occurs even when the level 


25 



of arsenic in the drinking water is about equal to that in Taiwan. Another 
consideration with regard to diet is that the low fat diets in Taiwan may have 
had a protective effect against cancer. Boutwell (1983) found that 
underfeeding animals in fat or calories diminished the cancer occurrence 
during the promotion stage of skin cancer. 

In summary, the metabolism and distribution data are important for 
evaluating the carcinogenic properties of arsenic. If the interconversion of 
inorganic arsenic to its methylated forms is saturable, then total urinary 
excretion of arsenic may be compromised at higher doses, leading to 
increased tissue levels. The available studies, however, do not contain 
sufficiont information for full evaluation of this hypothesis. In addition, the 
studies do not identify drinking water exposure levels for humans at which 
this process may be saturated. Thus, their influence on the carcinogenic 
process, either qualitatively or quantitatively, is uncertain, but merits further 
study. 


26 


V. Dose-Response Estimate for Arsenic Ingestion 


A. Introduction 

Dose-response assessment develops a numerical expression for the 
interrelationship between exposure and carcinogenic response at expected 
human exposure levels. Because this assessment often includes extrapolation 
from high doses used in animal studies to low doses in the region of human 
exposure and from animals to man, consideration of possible mechanisms of 
cancer development are important in deciding on the most appropriate 
extrapolation procedures for any particular chemical agent. For ingested 
arsenic, the dose-response estimate is based on human data (Tseng et al., 
1968; Tseng, 1977) for which the lowest dose level was about 10 pg/kg/day. 

Low-dose risk estimates based on customary linear assumptions would 
be overestimates if a threshold exists, or if risk decreases faster than linear as 
dose decreases. To study these questions, data on genotoxicity, pathology, 
metabolism, and pharmacokinetics were evaluated, particularly to help 
determine whether a nonthreshold or a threshold approach was more 
appropriate for this agent. Because the mechanism by which arsenic induces 
skin cancer in humans remains unknown and for other reasons developed 
below, the Technical Panel used a generalized multistage model with a time 
factor to develop dose-response information on the relationship between 
exposure to arsenicals and skin cancer in humans. 

1. Considerations Affecting Model Selection 

After evaluating several factors that might aid in selecting an extrapolation 
model for cancer risk, the available evidence is not persuasive as to any 
particular approach, and certain considerations seem to point in different 
directions. Some considerations suggest that a conservative approach- 
e.g., methods assuming that there is no threshold for carcinogenic 
response-is necessary to adequately predict arsenic risks for humans, 
while others suggest that nonthreshold assumptions will overestimate the risk 
to humans. 

For example, in deciding between nonthreshold and threshold approaches 
to the dose-response for arsenic, the development of skin lesions in persons 
exposed to arsenic was evaluated. Nonmalignant lesions (e.g., 
hyperpigmentation, hyperkeratoses), which are often observed before any 
indications of malignancy and more frequently than cancer, can serve as 
biological markers of exposure to arsenic. It is not clear whether these lesions 
can also be regarded as precursors to cancer that would identify an exposure 
threshold or level below which exposure to arsenic does not elicit a 
carcinogenic response. In particular, hyperpigmentation does not appear to 
progress to cancer, and data are not available on the progression of lesions 
that Yeh et al. (1968) called Type A hyperkeratosis. Although many squamous 
cell carinomas arise within pre-existing lesions, most basal cell carcinomas 
arise de novo. This means that Type A hyperkeratoses as a group cannot be 
viewed as precursors to all skin cancers. Thus, although the possibility of 


27 


using data on lesions to identify a threshold for arsenic-induced 
carcinogenesis is intriguing, additional information is needed before these 
observations could justify using threshold rather than nonthreshold 
assumptions. 

Other considerations suggest that a less conservative approach is 
appropriate. Since arsenicals do not appear to induce point mutations, one 
rationale for assuming low-dose linearity and using the generalized 
multistage model might not apply, and alternative, less conservative models 
should be considered. In this regard, structural chromosomal rearrangements 
that have been implicated in some cases of carcinogenesis could be 
expected to involve at least two "hits" and may imply a "theoretical" 
threshold. While such a "threshold" for cancer cannot be proven, any 
requirement for multiple "hits" would suggest a curvilinear dose-response 
relationship. Also, pharmacokinetic studies suggesting that tissue dosimetry 
of arsenic may change dramatically above some yet undisclosed exposure 
level suggest a nonlinear approach based on nonlinearity of dose. The role of 
tissue deposition in inducing carcinogenesis is not known but, consistent with 
dose-response theory, at higher target-organ doses greater biological 
effects would be expected. 

On balance, then, there is a paucity of information on the mechanism of 
carcinogenic action or the pharmacokinetics of arsenic that leads to 
confidence that any particular extrapolation approach is more appropriate than 
another. In these circumstances, it seems reasonable to use an extrapolation 
model with low-dose linearity to place an upper bound on the expected 
human cancer dose-response. It is considered an upper-bound estimate 
because the existing data on arsenic suggest that multiple hit or threshold 
considerations might apply to the extent these factors influence the 
carcinogenic process. Thus, in interpreting the risk estimate derived from the 
linear extrapolation, it is important to keep in mind the possibility that the 
model overestimates the dose-response to an unknown extent. Certainly, at 
least some high level exposures are associated with human carcinogenic risk, 
but as one decreases exposure, risks may fall off faster than linearity. The risk 
at low doses may be much lower than the current estimates, as low as zero, 
due to such factors as the metabolism or pharmacokinetics of arsenic. 

2. Changes in Methodology Relative to the 1984 Assessment 

In 1984, EPA estimated the unit risk for arsenic concentrations in drinking 
water using the data of Tseng et al. (Tseng et al., 1968; Tseng, 1977). Some 
modifications and additional considerations to the 1984 assessment are made 
in the current document to calculate a new risk estimate. These modifications 
include an adjustment for the larger amount of water believed to be 
consumed by the Taiwanese males in the study population as compared to 
persons in the United States. The previous estimate assumed that males and 
females in Taiwan and the United States drink 2 liters of water per day. The 
current estimate assumes that the Taiwanese male in the study population 
drinks 75% more water than does a person in the United States. The current 
assumption is based on the fact that the males of the study population 
performed heavy outdoor work in a very hot climate. As with the 1984 
analysis, the current analysis assumes that Taiwanese females consume the 
same amount of water per day as a person in the United States (2 liters per 
day). 

Also, the current analysis uses a life-table approach using age-specific 
U S. mortality data to calculate a lifetime risk of skin cancers from chronic 


28 


ingestion of water containing 1 ng/L of inorganic arsenic. The previous 
analysis produces an estimate of the risk of developing skin cancer from 
chronic ingestion of water containing 1 ng/L of inorganic arsenic by age 76.2 
years, assuming that one lived to that age. In addition, the current analysis 
uses a maximum likelihood approach, whereas the previous analysis used a 
least-squares linear regression of the prevalence rates. The maximum 
likelihood approach is considered a better approach because it takes account 
of the relatively small populations in the older age groups. Furthermore, the 
current analysis used both quadratic and linear dose terms, whereas the 
previous model was only linear in dose. The fit of the data to the model 
employing linear and quadratic terms is significantly better than if only a 
linear term is used (p < 0.05). 

The cancer risk estimate so derived is then used to predict the number of 
skin cancer cases that would occur in two other study populations exposed to 
arsenic via ingestion (Cebrian et al., 1983; Fierz, 1965) for comparison with 
the number that were actually observed in these studies. The details of these 
calculations are presented in Appendix B. 

B. Estimation of Risk 

1. Estimation of Risk Using Taiwan Data 

The study by Tseng et al. (1968) and Tseng (1977) (see Part III) provides 
the best available data for quantitative risk assessment. This study is useful 
for risk assessment for several reasons. First, it is a study of human 
populations, a point with obvious advantages for assessment of risk to 
humans. The exposed and comparison populations were large (40,491 and 
7,500, respectively), and prevalence rates in the exposed population were 
presented according to ages and levels of water concentration so that it is 
possible to estimate cumulative cancer incidence by age and dose level. The 
Technical Panel concluded that this study provides an adequate basis for 
quantitative risk assessment despite the important uncertainties. Of the three 
studies, it provides the largest study population, ascertained a large number 
of skin cancer cases, and reported responses by 12 dose and age groups. 

The quantitative assessment of hazard for arsenic ingestion uses the 
generalized multistage model with both linear and quadratic dose 
assumptions. These calculations show that for the U.S. population, the risk of 
developing skin cancer from lifetime exposure of 1 tig/kg/day ranges from 1 x 
10*3 to 2 X 10'3 (see Table B-4 in Appendix B). Flad Singapore skin 
cancer rates been used to calculate the background cancer rate for the 
Taiwanese population, the risk estimates are almost the same (see Table B- 
5). As in previous EPA risk assessments, including the 1984 arsenic risk 
assessment, the point estimate, rather than the 95% upper bound, is used 
when human data and a dose-response model with a linear term are used in 
the calculation. One reason for using the point estimate with human but not 
animal studies, is that human data usually involve exposure levels that are 
closer to the exposure range to which one wishes to extrapolate. Secondly, 
the difference between point and upper-bound estimates is of no practical 
significance when there is low-dose linearity. Assuming low-dose linearity 
holds for the Taiwan population, this is especially true for arsenic data 
because of the large population in that study. 

2. Comparison with Mexican Data 

Cebrian et al. (1983) (also described in Part III), conducted a prevalence 
study of skin lesions in two rural Mexican towns, one with arsenic- 


29 


contaminated drinking water. The data from this study are not as useful for 
quantitative risk estimation as those from the Taiwan study because there was 
only one dose group among the arsenic-exposed persons, and the study 
populations were relatively small (the exposed and comparison populations 
numbered 296 and 318, respectively). Moreover, this study identified only 
four cases of skin cancer. It is useful, however, to compare the dose- 
responses from the Taiwan study with those in the Mexican population 
studied. The generalized multistage model developed using the Taiwan data 
was used to predict prevalence rates for the Mexican population studied by 
Cebrian. 

These calculations show that the model developed from the Taiwan data 
provides a prediction of skin cancer risk that is consistent with the results of 
the Mexican study. 

3. Comparison with German Data 

The study by Fierz (1965) (Part III) was, like the Cebrian et al. (1983) 
study, not as suitable for quantitative risk estimation as the Taiwan study. The 
poor response rate of the potential study participants, the lack of a 
comparison group, and the lack of information on dosing patterns were the 
primary reasons why this study was not used for quantitative risk calculations. 
However, the results of this study, like those of Cebrian et al. (1983), were 
compared with estimates of prevalence derived from the Taiwan study. 

At the lowest dose in Taiwan (10.8 iig/kg/day), the prevalence rate of skin 
cancer was 2%. At the equivalent dose in the Fierz study, the prevalence rate 
of skin cancer is estimated as 3.4% to 15.4%. This 3.4% to 15.4% range is 
the result of the non-response among the potential study subjects described 
in Part II, Section A. Further explanation may be found in Appendix B. The 
Fierz data are not inconsistent with the prevalence of cancer estimated from 
the Taiwan data. Differences in skin cancer prevalence rates of these two 
study populations could be due to factors such as the following: the difference 
in exposure regimens and medium (Fowler’s solution is a mixture of 
potassium arsenite, potassium bicarbonate, alcohol, and water); the difference 
in the valence states of arsenic (potassium arsenite is trivalent arsenic, 
whereas the arsenic in the Taiwan wells was mostly pentavalent); other 
chemicals present: genetic differences among Taiwanese, Mexicans, and 
Germans (Caucasians could be more susceptible): and cultural or 
socioeconomic conditions. 

C. Summary of Dose-Response Evaluation 
1. Numerical Estimates 

Dose-response analysis for skin cancer resulting from exposure to 
arsenic in drinking water was performed on data from the epidemiologic study 
conducted in Taiwan. A generalized multistage model in time and dose was 
used for this analysis. The results were compared to data obtained from 
epidemiologic studies conducted in Mexico and Germany. These 
comparisons are not inconsistent with the risk estimates calculated from the 
Taiwan data. 

Based on the Taiwan data (Tseng et al., 1968; Tseng, 1977), the maximum 
likelihood estimate of lifetime risk of skin cancer for a 70-kg person who 
consumes 2 liters of water contaminated with 1 iig/L of arsenic per day is 
calculated to range from 3 x 10-5 (on the basis of Taiwanese females) to 7 x 
10-5 (on the basis of Taiwanese males): or, equivalently, the lifetime risk due 
to 1 pg/kg/day of arsenic intake from water ranges from 1 x 10-3 to 2 x 10 * 3 . 


30 


The skin cancer risk in the United States is unlikely to be greater than these 
estimates. 

2. Uncertainties 

As described above, qualitative uncertainties in the hazard identification 
include the possibility of competing mortality from Blackfoot disease, 
confounding by other chemicals, and lack of blinding of the investigators. In 
addition, the Technical Panel attempted to quantify two uncertainties in the 
dose-response evaluation: use of the Taiwan prevalence rate to estimate the 
cumulative incidence rate, and the influence of arsenic from sources other 
than drinking water on the Taiwan skin cancer prevalence. 

Regarding use of the prevalence rate, one assumption (see Appendix B) in 
using such data to estimate cumulative incidence rate is that the mortality 
rates are the same in diseased (skin cancer) and non-diseased individuals. 
As indicated previously, the arsenic-exposed population in Taiwan had an 
elevated risk of Blackfoot disease which has an earlier age of onset and a 
higher case-fatality rate than skin cancer. Also, persons with Blackfoot 
disease had a higher probability of having skin cancer than persons who did 
not have Blackfoot disease. This association of skin cancer and Blackfoot 
disease would have underestimated the risk of skin cancer due to arsenic 
since some of the persons with skin cancer and Blackfoot disease may have 
died before being observed in the Tseng et al. prevalence study. The 
Technical Panel made certain presumptions with respect to differential 
mortality and estimated its effects on the age-specific skin cancer incidence 
(see Appendix B). Based on this analysis, the Technical Panel estimated that 
differential mortality would underestimate the dose-response by no more 
than 50%. 

A countervailing uncertainty relates to arsenic intake by the Taiwan 
population. Since arsenic-contaminated water was used for vegetable 
growing and fish farming, food consumption could have been an important 
source of arsenic in the Taiwan population in addition to the water used for 
drinking. Not enough information is available on the arsenic content in food, 
however, for use in the risk calculation. Considering only arsenic in food 
contributed by water used for cooking, the dose-response may have been 
overestimated by 30% (see Appendix B). 

Finally, absent animal data or reliable human data under conditions of low 
exposure, the shape of the dose-response, if any, at low doses is uncertain. 

3. U.S. Populations 

To evaluate the contribution of arsenic exposure to the incidence of skin 
cancer in the United States, the Technical Panel considered estimating the 
number of cancer cases resulting from inorganic arsenic in the diet. The 
amount of inorganic arsenic in the diet, including drinking water and 
beverages, is between 17 and 18 pg/day (see Appendix E). The midpoint of 
this range, 17.5 pg/day, is equivalent to 0.250 pg/kg/day. Assuming that the 
amount of dietary inorganic arsenic has remained constant over the past 85 to 


31 


100 years (the longest expected lifetime), the annual number of skin cancer 
cases in the United States resulting from dietary inorganic arsenic would be 
1,684 cases per year, based on the data for Taiwanese males (see Table B- 
4, Appendix B). 8 

In a telephone conversation with Herman Gibb of the Carcinogen 
Assessment Group (May 1987), Dr. Joseph Scotto of the National Cancer 
Institute estimates that currently about 500,000 Caucasians in the United 
States develop invasive nonmelanoma skin cancer each year.9 Thus, the 
proportion of nonmelanoma skin cancer cases in the United States 
attributable to inorganic arsenic in the diet, the largest source of arsenic 
exposure for most Americans, is quite low (0.34%). '*0 

Even 0.34% is an overestimate for several reasons. First, the estimate of 
arsenically induced skin cancer for diet and drinking water is based on skin 
cancer prevalence data from the Taiwan study which includes both invasive 
and in situ carcinomas. Only 42% of 303 cases that were histopathologically 
examined in the Taiwan study were invasive nonmelanoma skin cancer cases; 
the balance (58%) were intraepidermal carcinomas. The estimated annual 
number of United States Caucasian nonmelanoma skin cancer cases cited 
above as 500,000 includes only invasive nonmelanoma skin cancer. Second, 
the Taiwan study involved clinical examination of individuals, while the 
estimate of 500,000 cases in the U.S. population was based on a review of 
clinical records. Ascertainment of cases will be better by actual examination 
than by a review of records where cases may not be recorded, all sources of 
records not examined, or sources of records which are examined are not 
available or lost. Third, the above estimates of arsenic-induced skin cancer 
in the United States resulting from arsenic present in the diet and drinking 
water is based only on the male data from Taiwan. The female data for 
Taiwan would give an estimate that is more than twofold lower. 

Finally, because of socioeconomic and ethnic differences between the 
United States and Taiwan, the Technical Panel’s draft report to the workshop 
stated that the applicability of these estimates to the U.S. population is of 
concern. Several workshop participants responded to this stated concern by 
noting that the United States was a culturally diverse society, as well as a 
society which included persons of all socioeconomic levels: thus, 
extrapolation from the Taiwan study to the United States was reasonable. 


SJhis IS based on a July 1, 1986, estimate of a U.S. population of 241,596,000 
people and the age distribution of the population at that point in time (U.S. Bureau 
of the Census, 1987). 

9Not enough information is available for races other than Caucasian with which to 
make reasonable estimates of annual nonmelanoma skin cancer cases. 

lOAIthough the denominator for this percentage is only Caucasian Americans, 
Caucasians constitute 85% of the U.S. population (U.S. Bureau of the Census 
1987). Furthermore, the incidence of nonmelanoma skin cancer among nonwhites is 
considerably less than that of whites (Scotto et al., 1983) so that the number of 
nonmelanoma skin cancer cases occurring each year among nonwhites is minima) 
in comparison to the 500,000 cases occurring among whites. 


32 



VI. Arsenic as an Essential Nutrient 


A. Background 

In 1983, the National Academy of Sciences reported that arsenic is an 
"essential" nutrient for humans. 

Research should also be designed to evaluate the possible 
essentiality of arsenic for humans--a requirement that has 
been demonstrated in four mammalian species. In the absence 
of new data, the conclusion reached in the third volume of 
Drinking Water and Health remains valid, i.e., if 0.05 mg/kg of 
dietary (total) arsenic is also a nutritionally desirable level for 
people, then the adequate human diet should provide a daily 
intake of approximately 25 to 50 jag. The current American diet 
does not meet this presumed requirement (National Academy 
of Sciences, 1983). 

A report prepared for ERA also concluded that arsenic is essential to human 
nutrition (O’Connor and Campbell, 1985), and ERA has relied on this 
assessment in a rule-making action (U.S. ERA, 1985). 

In the draft Forum report submitted for peer review, the Technical Ranel 
questioned this conclusion and the role that a nutritional requirement would 
have in risk assessment for cancer. At the December Reer Review Workshop, 
the Subcommittee on Essentiality summarized its conclusions on this 
question as follows: 

(1) Information from experimental studies with rats, chicks, 
mlnipigs, and goats demonstrates the plausibility^^ that 
arsenic, at least in inorganic form. Is an essential nutrient. 

A mechanism of action has not been identified and, as 
with other elements, is required to establish fully arsenic 
essentiality. 

(2) The nutritional essentiality of inorganic arsenic for 
humans is not established. However, the history of trace 
element nutrition shows that, if essentiality of an element 
for animals is established, it is highly probable that 
humans also require the element. Accordingly, knowing a 
mechanism of action is needed for a full interpretation of 
the currently available animal data. 

(3) The group consensus position is that, at this time, it is 
only possible to make a general approximation of 
amounts of arsenic that may have nutritional significance 
for humans. 


Emphasis added. The term “plausibility” refers to the term as employed in the 
framework described in Section B, subsection 2, of this part. 


33 



(4) Elucidation of the role of arsenic in human nutrition will 
depend upon development of specific information in the 
following areas: 

• biochemical and physiological mechanisms of action, 

• biological activity and metabolic response to various 
chemical 

• species of ingested arsenic, and 

• dose-response relationships between animal species. 

The scientific data on which these conclusions were based are summarized 
below,along with some concluding comments on the use of this information in 
the risk assessment process. 

B. Animal Studies 
1. Data Summary 

Two laboratories have independently reported that arsenic is an essential 
nutrient in goats and minipigs (Anke et al., 1976; 1978) and in rats and chicks 
(Uthus et al., 1983). 

In a two-generation study, Anke et al. (1976, 1978) compared goats and 
minipigs that were fed diets containing less than 50 ng arsenic/g (low arsenic) 
with control animals on diets supplemented with 350 ng arsenic/g."' 2 The diet 
was based on beet sugar and potato starch, with arsenic added to the 
supplemented diet as arsenic trioxide. There was no effect on the growth of 
the parental generation (Fq) animals. However, animals fed low-arsenic diets 
showed depressed fertility: only 58% of the goats and 62% of the minipigs 
conceived, as compared to 92% and 100% of controls, respectively. The 
offspring showed depressed birth weights (87% relative to the controls), 
depressed skeletal ash, and elevated perinatal mortality. Some of the low- 
arsenic lactating goats died; histological examination revealed ultra structural 
changes in the myocardium (Schmidt et al., 1984). 

Nielsen and coworkers studied the essentiality of arsenic in rats and chicks 
(Uthus et al., 1983). In the rat study, low-arsenic Sprague-Dawley dams 
were fed a diet containing 30 ng/g arsenic from day 3 of gestation. Controls 
received 4.5 iig arsenic (4.0 ng as sodium arsenate, the pentavalent form)/g 
and 0.5 n9 as sodium arsenite. Following weaning, the growth of low-arsenic 
offspring was slower than that of the arsenic-supplemented controls. The 
low-arsenic rats appeared less thrifty than controls and their coats were 
rougher and yellowish. Elevated erythrocyte osmotic fragility, elevated spleen 
iron, and splenomegaly were noted in these animals. 

In a separate three-generation study, dams were placed on a diet that 
contained less than 15 ng arsenic/g within 2 days of breeding. Controls 
received a supplement of 2 pg arsenic/g diet, as sodium arsenate. Growth 
depression was the most consistent effect of the low-arsenic diet observed 
throughout all three generations (Fi, F 2 , and F 3 ). In a replicate of this study 
(Uthus et al., 1983), only 2 of 12 low-arsenic Fi females became pregnant 


^ 2 Although investigators in this field often describe diets as arsenic “deficient” and the 
animals as arsenic “deprived,” since dietary arsenic levels are generally not 
established, the term “low-arsenic” is used here. Similarly, in most studies, the 
control animals were maintained on a diet supplemented with arsenic, rather than a 
standard commercial diet. For this reason, this report uses the term “supplemented” 
animals or diets. 


34 



compared to 9 of 12 controls, and the number of pups per litter was smaller in 
the low-arsenic group. 

In chicks, reduced arsenic (20 ng arsenic/g in the diet) depressed growth 
after 17 to 20 days (Uthus et al., 1983). In addition, these chicks had larger, 
darker livers, elevated zinc in the liver^^, elevated erythrocyte osmotic 
fragility, depressed alkaline phosphatase, and depressed white cell count, as 
compared to chicks on the supplemented diet. Some dose-effect information 
may be gleaned from these studies. In the course of these investigations, the 
arsenic content of the skim-milk powder base varied from 25 ng/g to 45 
ng/g. The most marked changes were found in animals ingesting the 25 ng/g 
diet. The chicks fed 45 ng arsenic/g did not differ from controls, indicating 
that this may be a minimum requirement for chicks. The presence or 
concentration of arsenic in the tissues of these animals was not reported. 

In an attempt to establish a biochemical function for inorganic arsenic, 
Nielsen and coworkers have shown nutritional interrelationships in studies 
using arsenic, zinc, and arginine (Uthus et al., 1983). Similarly, Cornatzer et 
al. (1983) have studied the role of arsenic in the biosynthesis of phosphatidyl 
choline (PC). They observed decreased PC biosynthesis in liver endoplasmic 
reticulum of Sprague-Dawley rats fed a diet containing 14 ng arsenate/g diet 
as compared with the values observed in rats maintained on a diet 
supplemented with 2 ppm (2 pg) arsenate/g diet. The authors hypothesized 
that the observed depression was not caused by a direct effect of arsenic on 
the enzyme system responsible for PC biosynthesis, but may have resulted 
from altered amino acid and/or protein metabolism. None of the studies to 
date have established a biochemical function for arsenic. 

Organic forms of arsenic enhance growth in poultry. The concentrations 
used to enhance growth are at least 500-fold greater than the levels used in 
the essentiality work. However, organic arsenic is less bioavailable. Thus, in 
these studies, the effective levels of inorganic arsenic may be comparable to 
those used in studies of essentiality. Many nutritionists feel that organic 
arsenic enhances growth in poultry by cleansing the intestinal gut of flora, an 
antibiotic action. Further work with animals whose guts have been sterilized 
would be useful in order to confirm this mechanism of growth enhancement 
and may be useful for interpreting the data on arsenic essentiality. 

2 . Evaluation of Data 

The December Workshop’s Subcommittee on Essentiality referred to a 
historical framework for the determination of nutritional requirements. 

Data pertinent to application of this framework were described previously 
in this report. Several laboratory studies described significant differences 
between animals maintained on low-arsenic diets relative to those on diets 
supplemented with this element. However, several factors limit the usefulness 
of these observations. 

Information on the composition and adequacy of the basal diets is 
particularly important in determining the specificity of the deficiencies 


i3The significance of elevated zinc in the liver is not known. 


35 



Framework for Determination of Nutritional Essentiality 


Empirical Observations 


- Establish Plausibility of Animal Models 


Reproducible Syndrome 


- Use of Chemically Defined Diets, Animal 
Models 


Biochemical Lesions 


- Characterize Specificity of Lesions 


Specific Biochemical Functions 
Absolutely Dependent on Factor ' 

Essentiality 


observed. For example, Uthus and Nielsen (1985) state that the baseline 
arsenic diet in their studies was borderline adequate in sulfur amino acids. 
Furthermore, because details of the diet preparation are not provided in 
Anke’s arsenic reports, the Technical Panel could not assess whether 
methods used to remove arsenic also destroyed other essential nutrients in 
the treated food."*^ Factors such as these make it difficult to evaluate fully the 
role of arsenic deficiency in the reported change in health status. 

Despite these limitations, the Technical Panel and Peer Review Workshop 
participants concluded that these studies provide sufficient information to 
suggest that a requirement for arsenic in animal diets is plausible, as 
contemplated in the first step of the framework. However, the available 
studies provide insufficient information to establish the remaining elements in 
the framework, i.e., "reproducible syndrome," "biochemical lesion," and 
"specific biochemical functions dependent on the factor. "15 Since the last two 
factors are particularly important, the essentiality of arsenic has not been 
rigorously established, even for animals. 

C. Applicability to Humans 

The Subcommittee on Essentiality cautioned (see point 3 of their 
conclusions stated above, and Appendix D) that definition of the requirement 
for arsenic in human nutrition must await the establishment of its essentiality. 
They agreed that an order of magnitude estimate is possible. They cautioned, 
however, that uncertainties influence such an estimate. Among these the 
reviewers cited lack of knowledge of a biochemical mechanism and 


^'^Certain procedures, such as acid washing of corn, were described; chelating agents 
were not used in preparation of the feed. (Dr. Anke was invited to the December 
workshop, but was unable to attend.) 

i5as explained in Appendix D, the written report of the Workshop Subcommittee on 
Essentiality is somewhat incomplete and ambiguous on the current status of steps 2 
and 3 in the framework, and the recollections of different workshop participants 
differ. Some believe that the group concluded that reproducibility (step 2) has been 
established by the animal data, while others believe that only plausibility (step 1) has 
been established. The individual comments presented in Appendix D suggest that 
there was a range of views among the reviewers and, perhaps, that the group was 
silent on step 2 in the written report because full agreement was lacking. 


36 



physiologic role, lack of knowledge of arsenic species in foods, lack of 
information on the validity of biological species comparison, and inability to 
specify how a putative intake requirement varies with developmental stage. 

Dose-effect information is lacking in the animal studies, which generally 
compare reduced-arsenic diets to the same diets with substantial 
supplemental arsenic (for example, 30 ng/g versus 4 tig/g). Despite that lack 
of information on arsenic levels in animal tissues or food intake that would 
allow estimates of arsenic doses, several methods have been used for 
quantitative extrapolations to estimate a human requirement. These methods 
described below, are highly speculative. Nielsen and coworkers cautiously 
estimated a human requirement of 30 to 40 ng/day based on the apparent 
adequacy for chicks of the diet containing 45 ng/g arsenic (Uthus et al., 1983). 
This estimate assumes that the same intake would be adequate for chicks 
and humans and that humans consume 700 to 1,000 g of food per day. In 
other papers, Nielsen estimated human requirements in another way. He 
assumed a dietary requirement for these animals could be somewhere 
between 6.25 and 12.5 ng/1,000 kcal. If humans and chicks consume calories 
in the same way, humans eating 2,000 kcal/day would require 13 to 25 iig 
daily. 

These two estimates are consistent with procedures used by nutritionists 
to estimate human requirements based on animal data. A method of 
extrapolation consistent with that used by toxicologists doing risk 
assessments for toxic effects would use information on the body burdens of 
animals consuming arsenic-adequate diets, and extrapolating from these 
data what a human would need to consume to achieve a similar body burden. 
For example, Nielsen’s chicks required 40 ng arsenic/g diet. Assuming that 
they weighed 0.40 kg and ate 50 g of food per day, they would consume 5 pg 
arsenic/kg/day. Hove (1938) concluded that 2 pg per day was adequate for a 
rat; this amount also extrapolates to a dose of 5 pg arsenIc/kg/day. If humans 
have a similar requirement, a 70-kg person would need about 350 pg 
arsenic/day, almost 10 times the current estimated adult intake. Since it does 
not appear that current arsenic intake produces arsenic deficiency, this 
procedure does not seem appropriate for nutritional extrapolation. An 
extrapolation based on surface area rather than body weight results in an 
estimate of 24 to 30 pg arsenic/day, which is more nearly consistent with the 
results of other methods. The estimates should therefore be interpreted as 
delineating a possible human nutritional requirement of the order of several 
tens of pg/day. 

The Technical Panel is not aware of case reports describing an arsenic 
requirement for humans, nor of experimental or epidemiologic-type studies 
designed to determine whether arsenic is essential. Furthermore, if arsenic is 
a required nutrient for humans, current environmental arsenic exposures are 
not known to produce human arsenic deficiency.is O’Connor and Campbell 


i^Even a well-controlled animal environment appears to provide enough arsenic to 
confound essentiality studies. In all of the studies of low-arsenic diets, special steps 
were taken to exclude extraneous arsenic from the animals’ environment. For example, 
goats were kept in polystyrene sties and supplied with cellulose litter. Frequently, more 
than one generation of low-arsenic exposures was required to produce effects 
attnbuted to arsenic deficiency. 


37 




(1985) noted that the Food and Drug Administration (FDA) Market Basket 
Surveys reported a decrease in arsenic (total dietary) from 68 to 21 ng 
arsenic/day between 1967 and 1974. The FDA has revised its total diet study 
and is currently reporting higher levels of dietary arsenic, which now may be 
fairly stable at approximately 46 pg arsenic/day (an unknown fraction is 
inorganic). Since most estimates of a human nutritional requirement for 
arsenic fall between 10 and 30 pg/day, the current estimated intake appears 
to be adequate. 

D. Summary and Conclusions 

Two groups of investigators have studied the essentiality of arsenic in 
control animals on conception rate, abortion rate, birth weight, growth, and life 
expectancy. The results of experiments in the chick and rat are less definitive. 
The diet used in the latter series of studies varied somewhat in arsenic 
content, rendering replication difficult, and necessitating use of an artificial 
diet which may have been borderline deficient in sulfur-containing amino 
acids. 

Despite some limitations in the available literature, the Technical Panel and 
the workshop participants concluded that the first step in the framework for 
essentiality has been established, that is, information from experimental 
studies with rats, chicks, minipigs, and goats demonstrates the plausibility 
that arsenic, at least in inorganic form, is an essential nutrient. 

With respect to the second step, identification of a reproducible syndrome, 
both the Panel and the workshop peer reviewers concluded that there is 
insufficient published information available to determine the reproducibility of 
the arsenic deficiency syndrome. Moreover, the framework outlined above 
does not require that this be unambiguously shown if a biochemical lesion is 
demonstrable. A mechanism of action has not been identified and, as with 
other elements, is required to fully establish arsenic essentiality. The 
evidence to date does not allow one to identify a physiological role for 
arsenic. 

In sum, the nutritional essentiality of inorganic arsenic for animals has not 
been established, but is a plausible assumption. If an element is required in 
animals, it is highly probable that humans also require it. Therefore, although 
no studies in humans on this question are known to the Technical Panel, a 
human requirement for arsenic is also possible. 

If arsenic were an essential element, one still does not know how to use 
that information in an assessment of cancer dose-response. One can say 
that the risks from arsenic deficiency would increase as a function of 
reductions in exposure below the threshold of essentiality. One might say that 
cancer dose-response decreases to the threshold for essentiality, but it does 
not follow that the cancer risk is zero at that point. It is possible that, at doses 
below an essentiality threshold, the overall risk to an individual would depend 
on both the cancer and deficiency-induced effects. 


38 


VII. Future Research Directions 


The significant information gaps identified in this report suggest future 
research directions relating to cancer risk assessment of ingested arsenic. 
Crucial gaps in the data base are found for (1) epidemiology, (2) mechanisms 
of arsenic-induced skin cancer, (3) metabolic phenomena involving arsenic 
in various species and its impact on the dose-response, and (4) essentiality. 
Much of the proposed research requires international cooperation. In addition, 
efforts among different parts of government and the private sector should be 
integrated for optimal data development. 

A. Epidemiologic Studies 

The Technical Panel has identified several data gaps that apply to 
previously conducted epidemiologic studies that are critical to further 
characterize and estimate the cancer risk for ingested arsenic. These points 
should be considered in ongoing and future studies: 

• level of species of arsenic exposures from all sources (e.g., soil, air, 
food, cooking water) including drinking water; better characterization of 
personal habits (e.g., water consumption, pica ingestion) also needed 

• further epidemiologic assessment of internal cancers 

• rates of Blackfoot disease mortality by age and its effects on the 
incidence of arsenic-associated cancer 

• studies of people who migrate in and out of areas with high levels of 
inorganic arsenic in drinking water to better ascertain the effects of age 
and dose on the cancer incidence 

• analysis of drinking water supplies for presence of contaminants other 
than arsenic, with special attention given to ergotamines 

• information on diet to determine whether there is a relationship between 
nutritional status and arsenic-induced cancers 

• identification of biological markers (e.g., genotoxicity, liver damage) 
which correlate with carcinogenic risk 

B. Mechanisms of Carcinogenesis for Arsenic-Induced Skin 
Cancer 

Studies are needed to help elucidate the mechanism of arsenic-induced 
carcinogenicity. Some ideas, which are identified below, have been proposed; 
however, the Technical Panel acknowledges that these are not all Inclusive. 

• in vivo studies of clastogenicity and further studies of the mechanisms 
underlying arsenic-induced genotoxicity 

• study of oncogene activation in pre-cancerous and cancerous lesions 

• the influence of arsenic on growth factors that may be related to cancer 
induction 

C. Pharmacokinetics/Metabolism of Arsenic 

A better understanding of pharmacokinetics and metabolism of arsenic is 
needed to support the assumptions made with regard to the shape of the 


39 


dose-response. It is critical in all such studies that accurate and precise 
methodology be used and that special attention be paid to sampling because 
of the potential for interconversion among arsenic species. 

• studies on metabolism and patterns of deposition in various tissues for 
acute and chronic exposure, in humans and animals, for arsenic and its 
methylated species 

• studies on variations in biomethylation in different tissues 

D. Essentiality 

Elucidation of the role of arsenic in human nutrition will depend on the 
development of specific information in the following areas: 

• biochemical and physiological mechanisms of action 

• biological activity and metabolic response to various chemical species 
of ingested arsenic 

• dose-response relationships between animal species 


40 


Appendix A 

Summary of Epidemiologic Studies and Case Reports 

on Ingested Arsenic Exposure 


41 


Table A-1. Summary of Epidemiologic Studies and Case Reports on Ingested Arsenic Exposure 


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(continued) 


Table A‘1. (Continued) 

Author Type of study Study population Results Highlights/deficiencies 

Central and 
South America 
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51 


poisoning was greater than those 
without disease. 


Table A-1. (Continued) 

Author Type of study Study population Results Highlights/deficiencies 


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53 


arsenic for the deceasecf children 
ranged from 0.128 mg/kg bw/day 
for the first year to 0.028 mg/kg 
bw/day in the seventh year. 



Table A-1. (Continued) 


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hyperkeratosis were reportecd. In 5 
patients, multiple carcinomas were seen; 
in untreatecj cases, regional lymph node 
metastases were seen. 


Table A-1. (Continued) 



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61 


feet; a variety of other symptoms were 
noted. The authors reported that 2 cases 
of cutaneous carcinoma had been 
reported in the same area; however, none 
were observed in this study. 




Table A-1. (Continued) 


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and lung cancer had taken an arsenical 
medicinal: another skin cancer patient had 
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64 


Lander et al., Case report 1 male angiosarcoma The patient had previously taken Fowler’s 

1975 patient solution. 





Table A‘1. (Continued) 


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Table A-1. (Continued) 


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(continued) 





Table A-1. (Continued) 


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67 


















Appendix B 

Quantitative Estimate of Risk for Skin Cancer 
Resulting from Arsenic Ingestion 


69 


Contents 


List of Tables . 71 

X 

List of Figures . 72 

I. Methodology . 73 

II. Application to Taiwan Epidemiologic Study . 73 

III. Use of the Mexican Data to Evaluate Taiwan’s Dose- 

Response Model . 79 

IV. Use of the German Data to Evaluate Taiwan’s Dose- 

Response Model . 83 

V. Discussion of the Uncertainties of the Risk Estimates . 85 

VI. Summary . 87 


70 










Tables 


B-1 Estimated distribution of the surveyed male population at risk (skin 

cancer cases) by age group and concentration of arsenic in well water 
in Taiwan . 75 

B-2 Estimated distribution of the surveyed female population at risk (skin 
cancer cases) by age group and concentration of arsenic in well water 
in Taiwan . 75 

B-3 Conversion of arsenic dose for Taiwanese to equivalent arsenic dose 
for U.S. population . 76 

B-4 Results of model fitting to Taiwan skin cancer data. 79 

B-5 Results of model fitting to Taiwan skin cancer data, adjusted for 

background rate . 81 

B-6 Lesions counted as skin cancers (ulcerative lesions and papular 
keratosis) in Mexico study, and predictions based on Taiwan 
experience, both genders combined . 82 

B-7 Conversion of arsenic dose for Mexicans to equivalent arsenic dose for 
U.S. persons . 82 

B-8 Skin carcinomas in patients treated with Fowler’s solution who were in 
the Fierz follow-up study . 84 

B-9 Age-specific incidence rates calculated from age-specific 

prevalence with equal and differential mortalities . 87 


71 











Figures 


B-1 Observed and predicted skin cancer prevalence for Taiwanese males 
at three exposure levels, by age; prevalence predicted by use of the 
model, linear in dose. 77 

B-2 Observed and predicted skin cancer prevalence for Taiwanese males 
at three exposure levels, by age; prevalence predicted by use of the 
model, linear and quadratic in dose . 77 

B-3 Observed and predicted skin cancer prevalence for Taiwanese 

females at three exposure levels, by age; prevalence predicted by use 
of the model, linear in dose . 78 

B-4 Observed and predicted skin cancer prevalence for Taiwanese 

females at three exposure levels, by age; prevalence predicted by use 
of the model, linear and quadratic in dose. 78 

B-5 Lifetime skin cancer risk for a U.S. person, predicted from the 

Taiwanese male experience. "Linear" = estimated by use of the 
model, linear in dose; "Quadratic" = estimated by use of the model, 
linear and quadratic in dose . 80 

B-6 Lifetime skin cancer risk for a U.S. person, predicted from the 

Taiwanese female experience. "Linear" = estimated by use of the 
model, linear In dose; "Quadratic" = estimated by use of the model, 
linear and quadratic in dose . 80 


72 








I. Methodology 

A generalized multistage model is employed to predict the prevalence of 
skin cancer as a function of arsenic concentration in drinking water (d) and 
age (t), assuming exposure to a constant dose rate since birth. Let F(t,d) 
represent the probability of developing skin cancer by age t after lifetime 
exposure to arsenic concentration d. The model has the following form: 

F(t,d) = l-exp[-g(d)H(t)] 

where g(d) is a polynomial in dose with non-negative coefficients, and H(t) is 
(t-w)k, where k is any positive real number, and t > w for induction time w. 
The model F(t,d) is a generalization of the multistage in which k can only 
assume the value of positive integers. The multistage model is consistent with 
the somatic mutation hypothesis of carcinogenesis (Armitage and Doll, 1954; 
Whittemore, 1977; Whittemore and Keller, 1978). It also results from the 
epigenetic hypothesis when reversible cellular changes occur randomly 
(Watson, 1977). Moreover, it can be derived from the multistage theory of 
carcinogenesis (Armitage, 1982). These authors and many others have used 
this model to interpret and/or estimate potency from human data. The number 
of people at risk and the number with skin cancer at different values of t and d 
must be known in order to employ maximum likelihood estimation (MLE). 

II. Application to Taiwan Epidemiologic Study 

In order to use the model described above and the prevalence data 
provided by Tseng et al. (1968) and Tseng (1977), the following three 
assumptions must be made: 

(1) The mortality rate was the same in the diseased (skin 
cancer) persons as in the nondiseased persons. 

(2) The population composition (with respect to the risk 
factors of the skin cancer) remained constant over time. 

This assumption implies that there was no cohort effect. 

(3) The skin cancer was not surgically removed. 

The first assumption may not be reasonable because there is reason to 
believe that the mortality rate in the diseased (skin cancer) persons was 
higher than in the nondiseased persons. Tseng et al. (1968) reported that 61 
skin cancer patients (out of a total of 428 individuals with skin cancer) had 
also incurred Blackfoot disease which was known to have higher death rates 
than the general population. The impact of this potential differential mortality 
will be investigated in Section V of this Appendix. The second assumption 
seems less a problem in view of the fact that the population studied by Tseng 
and his associates was stable. However, the probability still exists that there 
may be some cohort effect due to the change of risk factors, such as the 
change of the arsenic water concentration over time (over 60 years). The last 
assumption is reasonable because the studied population was very poor, and 
medical (surgical) service to the population was almost nonexistent. 

Tseng et al. (1968) and Tseng (1977) reported skin cancer prevalence 
rates as percentages specific to age group and arsenic concentration for each 
gender. The underlying "raw" prevalence ratios were calculated from the 
percentage estimates by use of data in Tseng’s 1968 publication. The use of 
these ratios permits use of all the data, including that for controls and the 0 to 
19 age group, which had not been included in EPA’s 1984 analysis. The 


73 


procedure used for estimating the actual number of persons at risk is 
presented in the paragraphs that follow. 

The percentage age distribution of the population in the endemic area by 
gender appears in Table 3 of Tseng et al. (1968). (Note that the percentages 
for males and females in the endemic area do not sum to 100.) Age group 

percentages were applied to the male population surveyed (19,269) to_ 

estimate the totals at each age. These were distributed among the four dose 
categories under the assumption that the age distribution of the surveyed 
males at each arsenic exposure category is the same. This was accomplished 
by solving a set of equations. Table B-1 shows the resulting distribution of 
the male population at risk. Furthermore, it was assumed that the distribution 
of surveyed females across age and dose categories was the same as that for 
men (see Table B-2). The age distribution of the control population appears 
in Table 3 of Tseng et al. (1968). Tables B-1 and B-2 also show the 
number of cancer cases observed in each age and dose group., 

Next, values of t and d representative of each age and arsenic 
concentration interval were determined. For each interval a weighted average 
age was calculated from the data in Table 3 of Tseng et al. (1968). The 
resulting values of t that relate to the skin cancer prevalence rate for males 
(females) are 8 (9), 30 (30). 49 (50). and 69 (68). 

From the distribution of arsenic concentrations in well water depicted in 
Figure 2 of Tseng et al. (1968), and the fact that the highest arsenic content in 
surveyed well water was 1.82 ppm, weighted average arsenic concentrations 
(in ppm) of 0.17, 0.47, and 0.80 were calculated for the low, medium, and high 
concentration groups, respectively. (This approach does not accommodate 
the variation with respect to time of the arsenic concentration in well water 
noted by the authors, but for which no data are available.) These values were 
then converted into equivalent doses for the U.S. person in units of jig/kg/day 
using the following assumptions: the "reference" U.S. person weighs 70 kg 
and consumes 2 L of water daily: the "reference" Taiwanese male weighs 55 
kg and consumes 3.5 L of water daily; and the "reference" Taiwanese female 
weighs 50 kg. The resultant arsenic dose rates, normalized to the reference 
U.S. person, are presented in Table B-3. 

These data were used with the generalized multistage model to predict 
dose- and age-specific skin cancer prevalence rates associated with 
ingestion of inorganic arsenic for the reference U.S. person based on the 
Taiwanese experience. The four dose groups include control, low, medium, 
and high. 

The model was fitted separately to the skin cancer data for males and 
females. The g(d) was evaluated as to linear and quadratic function of dose 
(i.e., two models were considered; one was linear in dose and the other was 
both linear and quadratic in dose). The MLEs of g(d), H(t), and the log 
likelihood (In L) estimate are shown in Table B-4. Table B-4 shows the unit 
risk, the probability that a U.S. person exposed to dose d = 1 ng/kg/day of 
arsenic in drinking water will develop skin cancer in lifetime. It is adjusted for 
the survivorship of the U.S. population by the life-table analysis. 

For visual inspection of the goodness-of-fit of the model with time, 
values of the observed skin cancer prevalence rates for Taiwanese males 
were given in Figures B-1 and B-2, for linear and quadratic dose, 
respectively. Figures B-3 and B-4 show the analogous plots for females. 
While the suitability for a particular model is not obvious from these plots, 
there is some evidence favoring the quadratic (both linear and quadratic in 
dose) model. For each gender-specific set of models, a test of the null 


74 



Table B-1. Estimated Distribution of the Surveyed Male 
Population at Risk (Skin Cancer Cases) by Age Group 
and Concentration of Arsenic in Well Water in 
Taiwan^ 


Arsenic 

concentration 

(ppm) 


Age group (years) 


0-19 

20-39 

40-59 

>60 

Total 

Low (0-0.30) 

2,714b 

935 

653 

236 

4,538 


(0)c 

(1) 

(4) 

(11) 

(16) 

Medium (0.30-0.60) 

1,542 

531 

371 

134 

2,578 


(0) 

(2) 

(18) 

(22) 

(42) 

High (> 0.60) 

2,351 

810 

566 

204 

3,931 


(0) 

(18) 

(56) 

(52) 

(126) 

Unknown 

4,933 

1,699 

1,188 

429 

8,249 


(0) 

(3) 

(61) 

(64) 

(128) 

Total 

11,540 

3,975 

2,778 

1,003 

19,296 


(0) 

(24) 

(139) 

(149) 

(312) 


apor the control group, the number of persons in each of the four age groups, 0- 
19, 20-39, 40-59, and > 60, are respectively 2,679, 847, 606, and 176. No 
skin cancer was observed in the control population. 

^Estimated number of persons at risk. 
cEstimated number of skin cancer cases observed. 


Table B-2. Estimated Distribution of the Surveyed Female 
Population at Risk (Skin Cancer Cases) by Age Group 
and Concentration of Arsenic in Well Water in 
Taiwan^ 

Arsenic Age group (years) 

concentration —- 


(ppm) 

0-19 

20-39 

40-59 

>60 

Total 

Low (0-0.30) 

2,651 b 

(0)c 

1,306 

(0) 

792 

(3) 

239 

(2) 

4,988 

(5) 

Medium (0.30-0.60) 

1,507 

(0) 

742 

(1) 

450 

(9) 

136 

(8) 

2,835 

(18) 

High (> 0.60) 

2,296 

(0) 

1,131 

(4) 

686 

(33) 

207 

(22) 

4,320 

(59) 

Unknown 

4,819 

(0) 

2,373 

(2) 

1,440 

(13) 

435 

(27) 

9,067 

(42) 

Total 

11,273 

(0) 

5,552 

(7) 

3,368 

(58) 

1,017 

(59) 

21,210 

(124) 


apor the control group, the number of persons in each of the four age groups, 0- 
19, 20-39, 40-59, and > 60, are respectively 2,036, 708, 347, and 101. No 
skin cancer was observed in the control group. 
hEstimated number of persons at risk. 

^Estimated number of skin cancer cases observed. 


75 









Table B-3. Conversion of Arsenic Dose 
for Taiwanese to Equivalent 
Arsenic Dose for U.S. 
Populations^ 

Taiwanese U.S. person 

(ppm) (pg/kg/day) 


Males 

0.17 

10.8 


0.47 

29.9 


0.80 

50.9 

Females 

0.17 

6.8 


0.47 

18.8 


0.80 

32.0 


^Assumptions: A U.S. person weighs 70 kg and 
drinks 2 L of water daily: a Taiwanese male weighs 
55 kg and drinks 3.5 L of water daily; a Taiwanese 
female weighs 50 kg and drinks 2 L of water daily. 


hypothesis that the coefficient corresponding to is zero is rejected at p < 
0 01 via the asymptotic likelihood ratio test. 

The estimated induction period (w), based on the experience of Taiwanese 
males, is approximately 6.9 years, and the estimated power of t is 2.9 (see 
Table B-4). Analogous estimates from Taiwanese females are 9.0 years and 
3.2. The risk for skin cancer estimated from the quadratic model (2 x 10*3 
and 1 X 10*3 per pg/kg/day) for males and females, respectively, is smaller 
than that estimated from the linear model (5 x 10*3 and 3 x 10*3 per 
pg/kg/day). With each model, the estimated risk for females is slightly less 
than the corresponding risk for males. Two reasons may explain why the risk 
estimate calculated on the basis of data for Taiwanese males is greater than 
that calculated on the basis of data for Taiwanese females; (1) the daily water 
consumption by Taiwanese males (3.5 LVday) In relation to that consumed by 
females (2 L/day) may be underestimated; and (2) males, in particular those 
who were healthy, were more likely than females to migrate out of town, and 
thus were not available at the time of the survey. 

The current U.S. drinking water standard for arsenic is 50 pg/L, which is 
equivalent to 1.4 pg/kg/day for the reference U.S. person. Figures B-5 and 
B-6 are plots of lifetime risk of skin cancer for a U.S. reference person as 
predicted from the model using the gender-specific Taiwan data. At 50 pg/L, 
the lifetime risk is estimated to range from 1 x 10*3 (based on data from 
Taiwanese females) to 3 x 10*3 (based on data from Taiwanese males) for a 
70-kg person who drinks 2 L/day of water contaminated with 50 g/L of 
arsenic. 

Lastly, age- and gender-specific nonmelanoma skin cancer incidences 
among Singapore Chinese (lARC, 1976) were used in the risk assessment as 
estimates of background skin cancer rates for Taiwan. The background rates 
for the four age groups, 0 to 19, 20 to 39, 40 to 59, and > 60 are, 
respectively, 0, 8.0 x 10*3, 6.7 x 10*^, and 3.6 x 10*3 for males, and 0, 7.0 
X 10*3, 5.5 X 10*4, and 1.1 x 10*3 for females. The purpose of using 
Singapore rates was to address the comment made by Margolis December 


76 




Figure B-1. Observed and predicted skin cancer prevalence forTaiwanese males 
at three exposure levels, by age; prevalence predicted by use of 
the model, linear in dose. 



Age 


Figure B-2. Observed and predicted skin cancer prevalence forTaiwanese males 
at three exposure levels, by age; prevalence predicted by use of 
the model, linear and quadratic in dose. 



77 













Figure B-3. Observed and predicted skin cancer prevalence for Taiwanese 
females at three exposure levels, by age; prevalence predicted by 
use of the model, linear in dose. 



10 42 74 


Age 


Figure B-4. Observed and predicted skin cancer prevalence for Taiwanese 
females at three exposure levels, by age; prevalence predicted by 
use of the model, linear and quadratic in dose. 



78 












Table B-4. Results of Model Fitting to Taiwan Skin Cancer 
Data 

Linear Quadratic 


Males: 

Doses (d): 0,10.818, 
g(d) = (0.302525 X 10-7)d 

H(t) = (t - 6.931)2 935 
In L = -614.551 

Unit risk (probability of skin cancer 
in lifetime due to 1 pg/kg/day 
of arsenic) 

= 5.0 X 10-3 
Females: 

Doses (d): 0, 6.8, 
g(d) = (0.682262 x 10-8)d 

H(t) = (t - 9.0)3 225 
In L = -348.041 

Unit risk (probability of skin cancer 
in lifetime due to 1 pg/kg/day 
of arsenic) 

= 3.4 X 10-3 


29.909, 50.909 pg/kg/day^ 

g(d) = (0.124707 X l0-7)d 

+ 0.404871 X 10-9)d2 

H(t) = (t - 6.873)2 950 

In L = -610.088 

Unit risk (probability of skin cancer 
in lifetime due to 1 pg/kg/day 
of arsenic) 

= 2.3 X 10-3 


18.8, 32.0 pg/kg/daya 

g(d) = (0.157281 X 10-3)d 

+ 0.204076 X 10-9)d2 

H(t) = (t - 9.0)3 231 
In L = -344.365 

Unit risk (probability of skin cancer 
in lifetime due to 1 pg/kg/day 
of arsenic) 

= 1.0 X 10-3 


aDose estimates for U.S. persons (see Table B-3). 
SOURCE: Data from Tseng et al., 1968. 


17, 1985 (Letter from Dr. Stephen Margolis, Ph.D., Centers for Disease 
Control, to Mr. Robert Dupuy, Director, Waste Management Division, U.S. 
ERA Region 8) that the lack of skin cancer found in the comparison 
population of 7,500 was anomalous. All Chinese populations for which skin 
cancer is reported have some incidence of skin cancer. The results of model 
fitting to the Taiwan skin cancer data, adjusted for this background rate, 
appear in Table B-5. Comparison of the unit risk estimates in Tables B-4 
and B-5 shows that this adjustment is inconsequential. Therefore, the final 
risk estimate used the background rate reported by Tseng et al. (1968). 

III. Use of the Mexican Data to Evaluate Taiwan’s Dose- 
Response Model 

Cebrian et al. (1983) studied persons residing in two rural Mexican towns, 
one with arsenic-contaminated drinking water. The prevalence of skin tumors 
observed by Cebrian was compared with rates predicted by use of the 
parameters estimated from Taiwanese data (see Section II of this Appendix). 
These calculations are discussed below. 

Cebrian et al. (1983) published age-specific prevalence rates of ulcerative 
lesions and papular keratosis among the surveyed groups (see Table B-6). 


79 





Figure B-5. Lifetime skin cancer risk for a U.S. person, predicted from the 
Taiwanese male experience. ''Linear'' = estimated by use of the 
model, linear in dose; ' 'Quadratic" = estimated by use of the model, 
linear and quadratic in dose. 



Environmental Doses ()wg/kg/day) 

Figure B-6. Lifetime skin cancer risk for a U.S. person, predicted from the 
Taiwanese female experience. "Linear" = estimated by use of the 
model, linear in dose; ' 'Quadratic" = estimated by use of the model, 
linear and quadratic in dose. 



80 
















Tdble B~5. Results of Model Fitting to Taiwan Skin Cancer Data, Adjusted for 
Background Rate^>b 


Linear 


Quadratic 


Males: 


Doses (d): 0, 10.818, 29.909, 50.909 ng/kg/dayc 


g{d) = (0.351576 X l0-7)d 

H(t) = (t - 6.934)2 885 
In L = -596.744 

Unit risk: 4.0 x lO'^ (pg/kg/day)"^ 


g(d) = (0.106619 X l0-^)d 

+ (0.558064 X 10-9)d2 

H(t) = (t - 6.867)2 903 

In L = -590.501 

Unit risk: 1.6 x 10'^ (ng/kg/day)*"' 


Females: 


Doses (d): 0, 6.8, 18.8, 32.0 pg/kg/dayc 


g(d) = (0.614891 X 10-8)d 

H(t) = (t - 9.0)3 225 

In L = -317.188 

Unit risk: 3.0 x 10*3 (jig/kg/day)*^ 


g(d) = (0.238789 X 10-9)d2 
H(t) = (t - 9.0)3 233 
In L = -309.892 

Unit risk: Not available due to nonlinearity. 


^Background rate used is nonmelanoma skin cancer incidence among Singapore Chinese 
(1968-1977) (lARC, 1976). 
hData from Tseng et al., 1968. 
cDose estimate for U.S. persons (see Table B-3). 


These prevalence rates, in 10-year age categories, were collapsed to form 
the age groups used in the Taiwan study: < 19, 20 to 39, 40 to 59, and > 60 
years. However, since the age distribution of persons over 60 years old 
differed significantly in the two towns, information on the prevalence of skin 
cancer in this age group is not included in this analysis. 

An evaluation of how well the model, based on the Taiwan experience, 
predicts the prevalence rates reported by Cebrian et al. (1983) is provided in 
Table B-6. Since the Mexican prevalence rates are not gender-specific, the 
Taiwan data for both genders were combined, normalized to dose equivalents 
in pg/kg/day for the reference U.S. person, and refitted to the model. For the 
same reason, it was necessary to convert the Mexican dose estimate to that 
of the reference U.S. person. This was done by assuming that a Mexican 
male (female) weighs 60 (55) kg and drinks 3.5 (2.5) L of water daily (Cebrian 
et al., 1983). If there were an equal number of males and females, the 
reference Mexican person would weigh approximately 57 kg and drink 3 L of 
water daily. The equivalent dose of arsenic, normalized to the reference U.S. 
person, appears in Table B-7. 

Cebrian et al. (1983) did not report gender difference in susceptibility to 
skin cancer from arsenic ingestion. There was a significant difference in the 
Taiwan study, however, where the crude male-to-female ratio was 2.9:1. 
For this analysis, attempting to ascertain how well the model, using the 
Taiwan data, might predict the skin cancer response in Mexico, the Taiwan 


81 




Table B-6, Lesions Counted as Skin Cancers (Uicerative 
Lesions [UL] and Papular Keratosis [PK]) In Mexico 
Study, and Predictions Based on Taiwan 
Experience, Both Genders Combined 


Arsenic 


Age group (years) 


concentration 

(ppm) 

0-19 

20-39 

40-59 

>60 

Control town 

UL (observed) 
PK (observed) 

0/201 a (0)b 
0/201 (0) 

0/73 (0) 
0/73 (0) 

0/29 (0) 
0/29 (0) 

0/15 (0) 
0/15 (0) 

Exposed town 

UL (observed) 
PK (obsen/ed) 
UL (predicted) 

0/187 (0) 
0/187 (0) 
0.08/187 (0.04) 

1/68 (1.5) 
8/68 (11.8) 
0.7/68 (1.0) 

2/27 (7.4) 
6/27 (22.2) 

1.2/27 (4.4) 

1/14 (7.1) 
1/14 (7.1) 


aQata from Cebrian et al., 1983. 
bPrevalence in percentages. 


Table B-7. Conversion of Arsenic 
Dose for Mexicans to 
Equivalent Arsenic Dose 
for U.S. Persons^ 

Mexican person U.S. person 

(ppm) (pg/kg/day) 


0.005 0.26 

0.411 21.63 


aAssumptions: A U.S. person weighs 70 kg 
and drinks 2 L of water daily; a Mexican 
person weighs 57 kg and drinks 3 L of water 
daily. 


response data for both genders were combined, normalized to dose 
equivalents for the reference U.S. person, and refitted to the model. The 
model, with linear and quadratic terms in dose, provides a significantly better 
fit than that with only a linear term (p < 0.01 by the asymptotic likelihood 
ratio test). The parameter estimates for the combined (i.e., sex-blind) data 
are: 


g(d) = (0.564398 x 10-8)d + (0.435613 x 10-9)d2 


82 







and 


H(t) = (t-8.0)3.028 

This is virtually a three-stage model (k = 3), with induction time of 8 years 
(w = 8). and quadratic in dose. 

Cebrian et al. (1983) reported that the estimated total dose and overall 
prevalence of lesions in the Mexican study were similar to those in the Taiwan 
study, except for skin cancer. As previously stated, Cebrian et al. (1983) 
separately described papular keratosis and ulcerative lesions that were 
considered compatible with a clinical diagnosis of epidermoid or basal cell 
carcinomas, but for which no histologic examination was available. The 
diagnosis of ulcerative lesions in the Mexican study corresponds to the 
diagnosis of skin cancer in the Taiwan study. 

The equation given above, with 21.63 ^g/kg/day as the dose rate for the 
reference U.S. person (i.e., the dose equivalent to the dose received by the 
exposed Mexican population) (see Table B-7) predicts the following 
prevalence of skin cancers by ages 19, 39, and 59, respectively; 0.04%, 
0.9%, 4.4% (see Table B-6). The responses observed in the age intervals 
0-19, 20-39, and 40-59 in the Mexican study are, respectively: 0.0%, 
1.5%, and 7.4%. The differences between the values predicted from the 
Taiwanese data and those observed in Mexico are negligible in view of the 
small number at risk in the latter study. Adjustment for background rate of 
skin cancer in the Mexican study increases the predicted prevalence by a 
negligible amount. 

IV. Use of the German Data to Evaluate Taiwan’s Dose- 
Response Model 

In 1984, a follow-up study of former patients who had been treated for 
skin disorders with Fowler’s solution (a solution of arsenic) between 1938 and 
1958 was conducted by Fierz (1965). (See II.A.3. for a description of this 
study.) 

The total doses in mL of Fowler’s solution and in tig/kg of body weight 
(assuming a 70-kg body weight) are shown in Table B-8. The crude 
response is the number of patients with skin cancer (total 21) out of those 
examined (total 262) by total dose. 

The "adjusted" response in Table B-8 (adjusted by isotonic regression) is 
based on the assumption that the true response rate is monotonically non¬ 
decreasing over total dose of Fowler’s solution: This assumption is probably 
not strictly true, since some variables not reported in the study (e.g., 
treatment regimen) differ among patients, and these differences are likely to 
affect the response. 

A rough comparison between the response rates in the study by Fierz (the 
"German" study) and the Taiwan study can be made by comparing response 
rates at equivalent total doses. The total dose (in ng/kg) in the Taiwan study 
for each dose rate and exposure combination is found by multiplying the daily 


83 


Table B~8. Skin Carcinomas in Patients Treated with 
Fowler’s Solution Who were In the Flerz 
Foilow-Up Study3 

Fowler’s solution Crude Adjusted 

(milliliters)response_response^ 


0 - 50 
50 - 100 
100 - 150 
150 - 200 
200 - 250 
250 - 300 
300 - 350 
350 - 400 
400 - 450 
450 - 500 
500 - 600 
600 - 700 
700 - 1,000 
1,000 - 1,500 
1,500 


0/24 ( 0.0) 
2/45 ( 4.4) 
2/24 ( 8.3) 
1/12 ( 8.3) 
1/14 ( 7.1) 
1/31 ( 3.2) 
1/17 ( 5.9) 
2/11 (18.2) 
2/11 (18.2) 
0/7 ( 0.0) 
1/18 ( 5.6) 
1/14 ( 7.1) 
2/13 (15.4) 
4/15 (26.7) 
1/5 (20.0) 


0/24 ( 0.0) 
2/45 ( 4.4) 
6/98 (6.1) 
6/98 (6.1) 
6/98 (6.1) 
6/98 (6.1) 
6/98 (6.1) 
6/61 ( 9.8) 
6/61 ( 9.8) 
6/61 ( 9.8) 
6/61 ( 9.8) 
6/61 ( 9.8) 
2/13 (15.4) 
5/20 (25.0) 
5/20 (25.0) 


^Response is given as no. carcinomas/no. patients at risk, and, in 
parentheses, as a percentage. 

^Estimate obtained by isotonic regression, assuming true response rates 
are monotonically non-decreasing as total dose increases. 

SOURCE; Fierz, 1965. 

dose rate by the total number of exposure days. Assuming an average 
bodyweight of 70 kg and a weight of 7.6 mg arsenic per mL of Fowler’s 
solution, we multiply the total dose in pg/kg by 9.2 x 10-3 to obtain an 
estimated equivalent dose in mL of Fowler’s solution (FS).'' The prevalence 
rate at the resulting total dose in the German study is then read from the 
adjusted response column in Table B-8. 

Exposures in the Taiwan study were far greater than those in the German 
study. At 10.8 pg/kg/day for 20 years, the total Taiwan dose corresponds to 
725 mL. At this dose, the prevalence rate for the Taiwan study is less than 
2%. At the equivalent dose in the German study, the prevalence rate is 


Vg arsenic/kg x lO'^ mg/|ig x 70 kg x 1/(7.6 mg arsenic/mL FS) = 9.2 x 10‘3 mL 
FS. 


84 





estimated to be 15.4% if 262 persons are considered at risk (see Table B-8) 
and 3.4% if 1,170 are at risk. 

Therefore, the difference in the prevalence rates at equivalent total doses 
estimated from the German study and observed in Taiwan are unknown but 
may be due to such factors as the difference in dosing regimens and media, 
the difference in arsenic species in well water in Taiwan and in Fowler’s 
solution, the mitigating effect of other chemicals present in well water, and 
genetic cultural or socioeconomic differences. 

V. Discussion of the Uncertainties of the Risk Estimates 

There are several factors that could affect the risk estimates presented in 
the Special Report. (Some of these factors have already been discussed 
elsewhere in that document.) In this section, two quantitative issues that 
received the most comments from peer reviewers are discussed and 
evaluated. 

The first issue concerns the use of prevalence rates to estimate the 
cumulative incidence rate. As discussed previously, for the prevalence data to 
be useful for the quantitative risk assessment, three assumptions must be 
made: 

(1) the mortality rate was the same in the diseased (skin 
cancer) individuals as in the nondiseased individuals. 

(2) the population composition (with respect to the risk 
factors of the skin cancer) remained constant over time. 

(3) the skin cancer was not surgically removed. 

The appropriateness of these assumptions have been discussed previously 
in this Appendix. The major concern was that the first assumption may not be 
appropriate and, thus it is of interest to assess the impact of differential 
mortality on the risk estimates. 

To calculate the age-specific skin cancer rate in the age-interval (x, 
x + t), the following notations are used: 

Pq = the skin cancer prevalence at age x 

Pi = the skin cancer prevalence at age x +1 

mo = the mortality rate in the nondiseased persons in the age- 
interval (x, x + t) 

mi = the mortality rate in the diseased persons in the age-interval 
(x, x + t) 

h = the age-specific skin cancer rate in the age-interval (x, x + t) 

The time to death or skin cancer is assumed to follow the independent 
exponential distribution with parameters mj, i = 0, 1, or h. The relationship 
between the age-specific skin cancer incidence rate, h, and the cumulative 
incidence, F(t), by time t, is given by 


f t 


Fit) = 1 - exp[- 


hix) dx] 
O 


Thus, it is sufficient to evaluate the effect of differential mortality on the 
age-specific incidence. 


85 



It IS shown (Podgor and Leske, 1986) that the age-specific incidence rate, 
h, satisfies the following equation. 


(1 -P^)P^exp(-m^-h) 


1-P 


1 


= Pq exp(-m^) -I- 


(1 -P^)h[expi-m^) - expi - m^ - h)] 


h 

From this equation, it is possible to investigate the effect of differential 
mortality on the age-specific skin cancer incidence. 

Recall that the risk estimates are calculated under the assumption that 
those persons with and without skin cancer had the same mortality rate. To 
assess how an increase of mortality rate in the skin cancer patients can affect 
the age-specific incidence rate, the skin cancer prevalence rates observed in 
the Taiwanese males (Table B-1) are taken as an example, and the age- 
specific skin cancer incidences in various age intervals are calculated using 
the formula given above. Table B-9 gives the estimated age-specific skin 
cancer incidence when the relative mortality rates between those persons with 
and without skin cancer are assumed to be (a) equal (m-i = mg), (b) two (m-i 
= 2mo), and (c) three (m^ = 3mo). 

From Table B-9, it is seen that the age-specific skin cancer incidence 
assuming differential mortality exceeds those assuming equal mortality, the 
Increase ranging from about 2% to 24% when the relative modality rate of 
two (mi = 2mo) is assumed; from about 2% to 49% when the relative 
mortality rate of three (mi = 3mo) is assumed. These observations are 
consistent with Dr. Lin’s comments that the difference between the cumulative 
incidence and the prevalence incidence will be higher in the "high" endemic 
area than in the "low" endemic area (Lin, 1987). 

Since the mortality rate in the diseased (skin cancer) persons is not likely 
to be three times greater than the nondiseased persons, the extent of risk 
underestimation does not appear to be of concern. 

The second issue concerns the intake of arsenic from the sources other 
than the drinking water. Arsenic intake from sources other than the drinking 
water would overestimate the unit arsenic risk calculated above from the 
Taiwan study. Heydorn (1970) reported that the blood arsenic levels were 
higher in the Taiwanese than in persons in Denmark, suggesting that both the 
study and comparison population in the Tseng study may have been exposed 
to arsenic from sources other than drinking water. However, these data are of 
limited use because the sample size is small (less than 20) and the sampling 
protocol is not specified. Since the arsenic-contaminated water was known 
to be used for vegetable growing and fish farming, the food consumption 
could have been an important source of arsenic intake in addition to the 
drinking water. There is very little information on the arsenic content in food, 
however, that can be used in the risk calculation. To provide some insight 
about how the arsenic intake from food consumption can affect the risk 
estimate, the consumption of rice and sweet potatoes is taken as an example. 

For the studied population, rice and sweet potatoes were the main staple 
and might account for as much as 80% of food intake per meal. For the 


86 




Table S-9. Age*-Specific Incidence Rates Calculated from Age- 
Specific Prevaience with Equal and Diffferentiai 
Mortalities 


SKin Cancer Age-Specific Incidence^ 


Exposure 

groupb 


Observed 
skin cancer 
prevalence 

Equal 
mortality 
mi = mo 

Differential mortality^ 

Age 

mi = 2mo 

o 

E 

CO 

II 

E 

Low-dose 

20-39 

1.07x10*3 

1.07x10*3 

1.09x10*3 

(2) 

1.11x10*3 

(4) 


40-59 

6.13x10*3 

5.94x10*3 

6.04x10*3 

(2) 

7.06x10*3 

(2) 


60-69 

4.66x10*2 

4.16x10*2 

4.84x10*2 

(16) 

5.56x10*2 

(34) 

Mid-dose 

20-39 

3.77x10*3 

3.78x10*3 

3.85x10*3 

(2) 

3.91x10*3 

(3) 


40-49 

4.85x10*2 

4.59x10*2 

5.30x10*2 

(2) 

6.06x10*2 

(3) 


60-69 

1.64x10*^ 

1.29x10*1 

1.57x10*1 

(22) 

1.85x10*1 

(43) 

Low-dose 

20-39 

2.22x10*2 

2.25x10*2 

2.29x10*2 

(2) 

2.33x10*2 

(4) 


40-59 

9.89x10-2 

8.17x10*2 

8.39x10*2 

(3) 

8.61x10*2 

(5) 


60-69 

2.54x10*1 

1.89x10*1 

2.34x10*1 

(24) 

2.81x10*1 

(49) 


ajhe mortality rates for those without skin cancer are assumed to be 0.035, 0.26, 
and 0.25 respectively for the age-intervals 20 to 39, 40 to 59, and 60 to 69. 
bpor the low exposure group, Pq = 0, Pi = 1.07x10*3 for the age-interval 20 to 
39; Pq = 1.07x10*3; P^ = 6.13x10*3 for the age-interval 40-59; Pq = 
6.13x10*3; P^ = 4.66x10*2 for the age-interval 60+ (assumed to be 60 to 
69). For other exposure groups, Pq and P^ are similarily defined. 
cThe parenthesized values are the ratio (xlOO) of age-specific skin cancer 
incidence rates calculated respectively under the assumptions of the differential 
mortality and equal mortality. 


purpose of discussion we will assume that a man in the study population ate 
one cup of dry rice and two pounds of potatoes per day and that the amount 
of water required to cook the rice and potatoes was about 1 L. Under this 
assumption, the risk calculated before is overestimated by about 30% (1 \J3.5 
L). This calculation considers only the water used for cooking; the arsenic 
content in the rice and potatoes that might have been absorbed from soil 
arsenic is not considered because of the lack of information. For a realistic 
adjustment of the risk estimates, one would need the information on the 
arsenic content and the composition of the diet taken by the studied 
population whose diet content was certainly different from the population 
currently living in the same area. 

VI. Summary 

This section presents a dose-response analysis for skin cancer from 
exposure to inorganic arsenic in drinking water. Results based on the 
multistage theory of carcinogenesis have been obtained from the Taiwan 


87 





epidemiologic study and are compared to two studies in other environments 
(Mexico: Cebrian et al., 1983; and Germany: Fierz, 1965). Compatibility of 
results across studies (1) suggests the conclusion that arsenic exposure is the 
likely causal factor in the increased prevalence of skin cancers in these 
studies: (2) provides additional statistical evidence for refinement of statistical 
estimates; and (3) helps to identify potential sources of variability and 
environmental factors, or patterns of exposure, that may be influential. 

None of these studies contains all of the details needed for an ideal 
statistical analysis, such as: ages at times of initial exposure, termination of 
exposure, and first appearance of skin cancer; similar information on lesions 
that may frequently precede appearance of skin cancer; number of subjects 
with cancer at multiple sites; locations of cancers; and prior disease including 
those that lead to the use of Fowler’s solution. Consequently, it is important to 
glean what information is available from each study for purposes of 
complementarity as well as comparison. 

Analysis of the Taiwan data required estimation of the number at risk in 
each dose/age category because only response rates and marginal totals by 
age groups are provided. The estimated values, which fit the marginal data 
closely, make possible the estimation of dose-response for the generalized 
multistage model by means of maximum likelihood. The cancer response is 
well described by a quadratic polynomial in dose (with positive linear 
coefficient) for both male and female data. The minimum tumor induction time 
is estimated at 7 and 9 years for males and females, respectively; in both 
cases, the cancer response for time-to-tumor is best described by time of 
observation (minus induction time) to the third power. The observed data in 
the Mexican study, taken at only one concentration of arsenic in well water, 
but collected for different exposure intervals, are consistent with predictions 
from the model using the Taiwan data. 

The data from the study in Germany consist of the response of former 
dermatology patients who had been treated with Fowler’s solution (a 0.5% 
solution of arsenic trioxide, which is a relatively toxic form). Patients were 
treated for up to 26 years (many for apparently a much shorter period) in 
intermittent dosing patterns specific to the prescribed treatment. This is in 
contrast to exposure to arsenic-contaminated well water which is likely to be 
consumed at a reasonably uniform rate over time. 

The published data do not include much information that could be useful 
for risk assessment. Except for a few specific cases cited here, the data were 
summarized by response for total dose. When compared to predictions from 
the model for Taiwan with total dose held fixed at values equivalent to total 
doses in the German study, and then varied over a wide range of possible 
exposure durations in the Taiwan data, the skin cancer prevalence values in 
the German study exceeded the values predicted. 

In conclusion, the lifetime risk of skin cancer for a 70-kg person who 
consumes 2 liters per day of water contaminated with 1 pg/L of arsenic is 
calculated to range from 3 x 10-5 (on the basis of Taiwanese females) to 7 x 
10-5 (on the basis of Taiwanese males): equivalently, the lifetime risk due to 
1 ng/kg/day of arsenic intake from water ranges from 1 x 10-3 to 2 x 10-3- 


88 


Appendix C 

Internal Cancers Induced by Ingestion Exposure to 

Arsenic 


89 


Internal Cancers Induced by Ingestion Exposure to 

Arsenic 


As noted in the Technical Panel’s Special Report on Ingested Inorganic 
Arsenic, arsenic ingestion has been associated with cancer of internal organs. 
Chronic arsenic ingestion has been reported to be associated with cancer of 
the lung (Calnan, 1954; Robson and Jellife, 1963; Fierz, 1965; Chen et al., 
1985, 1986), bladder (Sommers and McManus, 1953; Nagy et al., 1980; Chen 
et al., 1985, 1986), liver (Fierz, 1965; Regelson et al., 1968; Lander et al., 
1975; Popper et al., 1978; Roat et al., 1982; Falk et al., 1981; Chen et al., 
1985, 19^), nasopharynx (Prystowsky et al., 1978), kidney (Chen et al., 1985; 
Nurse, 1978), and other internal organs (Rosset, 1958; Reymann et al., 1978; 
Chen et al., 1985). Many of these references are case reports, however, and 
do not deserve the attention given a well-designed epidemiologic study. 

The Technical Panel felt it important to summarize the studies of Chen et 
al. (1985, 1986) since these studies have been referred to in the text of the 
Technical Panel’s report, and they are of a design which allows one to give 
greater weight to observed associations. Chen et al. (1985) calculated cancer 
standardized mortality ratios (SMRs) for the population of the arsenic endemic 
area studied by Tseng et al. (1968). The authors found the SMRs for cancer 
of the kidney, bladder, skin, lung, liver, and colon to be significantly elevated 
in both males and females. Chen et al. (1986) conducted a case-control 
study of lung, bladder, and liver cancer mortality cases and randomly 
sampled controls from the endemic area. They found odd ratios that were 
significantly (p < 0.05) elevated, and remained much the same when 
adjusting for other risk factors including cigarette smoking. Chen et al. (1985) 
indicated a positive correlation between the SMRs of those cancers which 
were significantly elevated and Blackfoot disease prevalence rates. Also, 
SMRs were greater in villages where only artesian wells were used as the 
drinking water source than in villages using shallow wells only. Chen et al. 
(1985) stated that water from the artesian wells in the Blackfoot disease 
endemic areas had been reported to have from 0.35 to 1.14 ppm arsenic with 
a median of 0.78 ppm while the shallow well water had arsenic content 
between 0.00 and 0.30 ppm with a median of 0.04 ppm. Chen et al. (1986) 
found an increased risk of lung, bladder, and liver cancer with increasing 
duration of artesian well use. Thus, in both studies (Chen et al., 1985, 1986), 
the authors demonstrated a qualitative relationship between arsenic exposure 
and internal cancer risk; however, the data is not sufficient to assess the 
dose-response. For this purpose, it is necessary to have the individuals 
studied by Chen grouped by well-water arsenic concentration and age. 
These data quite likely do (or did) exist, because they were available to Tseng 
et al. (1968) for the skin cancer study. EPA is currently trying to obtain these 
data. 


90 


Appendix D 

Individual Peer Review Comments on Essentiality 


91 


Individual Peer Review Comments on Essentiality 


This appendix seeks to clarify some uncertainty in the workshop report of 
the Subcommittee on Essentiality. 

The Subcommittee on Essentiality of the December 2-3, 1986 peer 
review workshop reported that "information from experimental studies with 
rats, chicks, minipigs, and goats demonstrates the plausibility that arsenic, at 
least in inorganic form, is an essential nutrient. A mechanism of action has not 
been identified and, as with other elements, is required to establish fully 
arsenic essentiality."1 

The Subcommittee also described a framework for determination of 
nutritional essentiality. The framework describes the usual approach to 
establishing essentiality as including: 

1) performance of empirical observations in animal models 
to establish the plausibility of nutritional essentiality: 

2) establishment of a reproducible syndrome through the 
use of chemically defined diets in animal models: 

3) definition of biochemical lesions to characterize the 
specificity of the lesions: 

4) establishment of specific biochemical functions 
absolutely dependent on the factor being investigated. 

The Subcommittee’s statement on the animal studies clearly addresses 
points 1 and 4 in the framework, but the written report does not explicitly 
address points 2 and 3 for the animal studies. Furthermore, Agency 
participants and some Subcommittee members contacted by telephone 
differed somewhat in their recollection of the Subcommittee’s opinion on the 
extent to which points 2 and 3 in the above hierarchy had been 
experimentally achieved. Some selected peer reviewers’ comments and 
observers’ notes are summarized below to explain the Technical Panel’s 
position on this issue. The summary report of the Risk Assessment Forum 
Peer Review Workshop on Arsenic (U.S. EPA, 1987) presents all of the post¬ 
workshop comments in full. 

I. Comments on Plausibility of Arsenic Essentiality in Animals 

A. PosUWorkshop Comments on Essentiality [page numbers 
refer to the summary report of the Peer Review Workshop 
on Arsenic (U.S. EPA 1967)] 

Menzel: The section [in the peer review draft] on [essentiality] of 

arsenic should be rewritten with a more positive emphasis 
on the probable [essentiality] of arsenic. . . (p. E-17). 


^ Report of the EPA Risk Assessment Forum Peer Review Workshop on Arsenic, 
December 2-3, 1986. 


92 



Mushak: . . .the overall conclusion would seem to be that it is 

premature to conclude that essentiality is established (p. E- 
21 ). 

Weiler: It appears that there may be enough experimental evidence 

to suggest that in some animals, diets low in arsenic affect 
growth and fertility. However, the levels in the arsenic 
depleted diet are about the same as those found in the 
normal human diet (<50 ng/g). Further, the amount of 
arsenic added as a supplement (2 pg/g) are far in excess of 
what would be found in the normal human diet. 

Further, the supplementary arsenic is all inorganic, whereas 
the arsenic in the human diet is, in all likelihood, almost all 
organic. Thus, the amount of inorganic arsenic in the human 
diet (excluding drinking water) is really quite small (perhaps 
a few ng/day), but there are no apparent health effects that 
have been observed in humans. The relevance of the animal 
experiments to humans is therefore not at all clear and it 
seems unrealistic to believe that arsenic is needed in 
quantities greater than what is present in the normal western 
diet (pp. E-43 through E-44) 

8. Oral Comments Drawn from ERA Notes of Meeting: 

- The absence of knowledge of biochemical action for arsenic and of 
cofactor requirements renders a determination of essentiality 
uncertain (methyl donors, vitamin C, choline, molybdenum, arginine, 
and histidine were cited as possible cofactors). [Fox; Combs; general 
2 ] 

- Reproductive experiments are difficult to perform and not always 
reproducible. Discussants referred again to lack of knowledge of 
possible cofactors. [Nielsen; Menzel; general] 

- Progression of steps leading to the establishment of essentiality is 
necessary. Several participants felt that research is now in an early 
stage (i.e., step 2, establishment of a reproducible syndrome). 
[Combs; general] 

- Some reviewers emphasized that the steps in the framework need 
not all be unambiguously established, e.g., identification of a specific 
biochemical lesion and mechanism would suffice even in the 
absence of a clear definition of a reproducible syndrome, [general] 

11. Estimation of a Human Nutritional Requirement for Arsenic 

The Subcommittee’s report states ". . .at this time it is only possible to 
make a general approximation of amounts of arsenic that may have nutritional 
significance for humans. "3 


2 General discussion. Individual attribution uncertain. 

3 Report of the EPA Risk Assessment Forum Peer Review Workshop on Arsenic, 
December 2-3, 1986. 


93 



A. Post-Workshop Comments [page numbers refer to the 
summary report of the Peer Review Workshop on Arsenic 
(U.S. EPA 1987)1 

Menzel: . . .the development of the estimate for the human daily 

requirement is quite limited and careful delineation of the 
limits should be included. . . .uncomfortable about providing 
a single estimate and would encourage the provision of a 
range of values citing the uncertainties in the methods of 
estimation and the interactions between arsenic and methyl 
donor. . .availability in the diet (p. E-17). 

Strayer: I feel that a certain tone could be struck by the report to 

indicate that evaluating the question of lower limits for 
arsenic in drinking water is not so much a matter of direct 
proof of essentiality in any species. Rather, the fact that the 
possibility of essentiality has been raised by workers in 
widely disparate species and settings should deter us from 
setting very low limits even if proof of its essentiality in man 
is not forthcoming (p. E-30). 

B. Oral Comments Drawn from Observers Notes of Meeting 

- Discussants outlined reasons for not providing an estimate of 
nutritional requirements for arsenic at this time: the fact that there is 
no information on speciation of arsenic in the diet; analytical 
difficulties; species-comparative problems (e.g., uncertainty on 
whether to make direct weight comparisons or to use surface area 
conversions); lack of a biochemical mechanism; and lack of 
knowledge of arsenic requirements as a function of age. [general] 

- Discussants reached a consensus that development of an order- 
of-magnitude estimate of intake requirements is possible. However, 
they felt that the factors influencing the uncertainty of such an 
assessment (as listed above) should be spelled out. [general; 
subcommittee report 

III. Use in Risk Assessments 

Andelman: At the workshop it was the consensus that the essentiality of 
arsenic has not been proven for humans. . . .Nevertheless, 
there does seem to be some confusion in that the question 
of essentiality has become somewhat intertwined with that of 
the risk for skin cancer, and this is inappropriate. The risk of 
skin cancer is unlikely to be influenced by the possible 
essentiality of arsenic. The use of the risk model to regulate 
arsenic should take into account such a possibility, but there 
does not appear to be a basis for doing so at this time (p. 
E-6). 


^ Report of the EPA Risk Assessment Forum Peer Review Workshop on Arsenic, 
December 2-3, 1986. 


94 



Menzel: As a consequence of the agreement of the workshop 

participants on the probable essentiality of arsenic, a new 
section will have to be added to deal with [the] problem [of 
essentiality versus toxicity]. . . .EPA should face . . .the 
problem of the no-threshold treatment of oncogenesis and 
the threshold phenomenon of essentiality. . . . 

I see no need to abandon the no-threshold treatment for 
oncogenesis even though arsenic or other minerals might be 
essential. To not face this issue directly will only encourage 
misunderstanding and disagreement with the risk estimate 
(pp. E-18 through E-19). 

Mushak: It is premature to factor essentiality into risk assessment 
models for arsenic exposure in human populations. . . .There 
is no inherent limitation on the use of linear extrapolation 
models for, e.g., skin cancer, because of any threshold 
implicit in a daily required intake (p. E-21). 


95 







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Appendix E 

Metabolic Considerations 


Prepared by: 


Dr. William Marcus 
Dr. Amy Rispin 


97 


Contents 


List of Tables . 99 

List of Figures . 99 

I. Introduction . 100 

II. Exposure Levels of Arsenic; Chemical Forms and Availability ... 100 

A. Drinking Water . 101 

B. Ambient Air . 101 

C. Food . 101 

D. Occupational Exposed Groups. 103 

E. Total Daily Body Burden . 103 

III. Metabolism, Bioavailability, and Toxicity . 103 

A. Toxicity of Arsenic Chemical Species . 103 

B. Absorption, Distribution, and Elimination . 104 

C. Detoxification via Methylation . 106 

D. Human Metabolism and Enzyme Kinetics . 109 

IV. Pharmacokinetics of Arsenic Metabolism and Its Implications for 

Oncogenicity . 113 


98 
















Tables 


E-1 Percentage of inorganic arsenic in food: a preliminary analysis 102 
E-2 Daily arsenic body burden (pg/day) in the United States . 104 

Figures 

E-1 Reproduction of arsenic III forms by membrane-bound 

lypoic acid . 107 

E-2 Role of s-adenosylmethionine in methylation of 

arsenic III . 107 

E-3 Urinary concentrations of arsenic and its metabolites . 110 

E-4 Excretion of arsenic metabolites following a single oral dose 

of inorganic arsenic: 74 As radioactivity in urine of male volunteer 

No.5; ingested dose 6.45nCi . Ill 

E-5 Urinary excretion of arsenic (As) and its metabolites in 

glass workers with prolonged exposure to Arsenic trioxide 
(AS2O3) after suspension and resumptions . 113 


99 








I. Introduction 

The Technical Panel has concluded that ingestion of inorganic arsenic can 
produce a dose-related carcinogenic response in humans. There are many 
uncertainties including the mechanism of action of arsenic as a human 
carcinogen. The Technical Panel has explored the bioavailability, toxicity, and 
carcinogenicity of the different chemical forms of arsenic which comprise the 
U.S. body burden and outlined this information in broad overview in this 
Appendix. However, the Panel expects that EPA program offices will use their 
own information developed for particular conditions of human exposure, along 
with the information presented in this Appendix, to develop a complete risk 
assessment for this compound. 

This Appendix also delineates the metabolic pathways of absorption and 
the daily ingested amount of arsenic at which excretion and elimination of 
arsenic occur. The many new studies available on arsenic metabolism may 
offer explanations for some of the observations reported in the epidemiologic 
studies, provide a basis for speculation about the role of some of these 
metabolic factors in the carcinogenesis of arsenic, and suggest avenues for 
future research. Although much of the data on pharmacokinetics Is derived 
from acute or short-term exposures, a number of observations are cited of 
populations chronically exposed occupationally or through drinking water and 
food. However, the Panel remains uncertain about the applicability of this 
information in toto to carcinogenesis developing under conditions of chronic 
exposure. The Panel believes, however, that information and analyses of this 
type will be useful in future assessments of the risks associated with human 
exposure to arsenic. 

Part III reviews information on sources of arsenic to provide data on the 
body burden of arsenic in the U.S. population. In Part III data relating to the 
metabolism and toxicity of arsenic are reviewed as background for the 
discussion in Part IV of metabolic considerations that may help elucidate the 
mechanism by which arsenic effects carcinogenic changes in humans. 

II. Exposure Levels of Arsenic; Chemical Forms and Availability 

Arsenic Is a natural constituent of certain rock and mineral formations in 
the earth’s crust. Weathering of rocks and minerals appears to be a major 
source of arsenic found in soils and drinking water sources. Other causes of 
arsenic In soil are deposition and precipitation of airborne particles from 
industrial operations, application of arsenic-containing pesticides, and decay 
of contaminated plant material. As a result of its ubiquitous nature, humans 
are exposed to arsenic primarily in foodstuffs and drinking water, and for 
certain target groups, from industrial and agricultural uses (U.S. EPA, 1985). 
Among individuals of the general population, the main routes of exposure to 
arsenic are via ingestion of food and water; lesser exposures occur via 
inhalation. Among smokers, intake by inhalation is augmented in proportion to 
the level of smoking because of background levels of arsenic in tobacco 
(Weiler, 1987; lARC, 1986). 


100 


A. Drinking Water 

Drinking water contains arsenic predominantly as inorganic salts in the tri- 
valent and pentavalent states. These inorganic salts are fully available 
biologically and quite toxic in very high concentrations. In chlorinated drinking 
water supplies, all arsenic salts have been found to be pentavalent as a result 
of oxidation by free chlorine. 

The results of federal surveys of public water supplies and compliance 
monitoring data developed by the states are summarized below (U.S. EPA, 
1984b; U.S. EPA, 1985). Most of the approximately 214 million people in the 
United States using public water supplies are exposed to levels of arsenic 
below 2.5 lag/L. Assuming an average daily consumption of 2 liters of water, 
most of the U.S. population would thus be exposed to less that 5 iig of 
arsenic per day from drinking water. However, some U.S. drinking water 
supplies contain higher concentrations of arsenic. Based on the compliance 
monitoring data available through the Federal Reporting Data Systems, one 
can estimate that approximately 112,000 people are receiving drinking water 
from public water supplies with arsenic levels at or above 50 ng/L, the current 
Maximum Contaminant Level. These people would be exposed to more than 
100 \iQ of arsenic per day. These surveys do not include many wells currently 
in use in the United States. On the average, ground water supplies show 
higher levels of arsenic in some of the western United States. 

B. Ambient Air 

Assuming a daily inhalation rate of 20 m3, and an average national 
exposure of 0.006 ng arsenic/m3, the inhalation exposure of the general 
public to water-soluble forms of arsenic in ambient air can be estimated as 
almost 0.12 ng/day. Assuming 30% to 85% absorption of inhaled arsenic, 
depending on the relative proportions of vapor and particulate matter (U.S. 
EPA, 1984a: Vahter, 1983), the general public would be exposed to a range of 
approximately 0.04 to 0.09 pg/day of arsenic by inhalation. 

Persons living near industrial areas such as smelters, glass factories, 
chemical plants, or cotton gins may be exposed to ambient air levels between 
0.1 and 3.0 pg arsenic/m3 (U.S. EPA, 1984b). This would result in as much as 
45 pg arsenic absorbed per day. 

In the general environment, airborne arsenic is available from a variety of 
sources as inorganic salts. In the vicinity of smelters, these salts contain 
trivalent arsenic. The chemical form and the uptake rate of arsenic in the 
vicinity of cotton gins from its use as a desiccant on cotton is not known. 

C. Food 

In the United States, arsenic is used as a pesticide on grapefruit, grapes, 
and cotton. In addition, the animal feed use of cotton, grapes, and grapefruit 
byproducts can lead to arsenic residues in meat and milk. Various organic 
forms of arsenic (arsanilic acid, roxarsone, and carbarsone) are added to feed 
as growth enhancers for chickens and swine (Anderson, 1983). Finally, many 
food-stuffs contain arsenic from background environmental contamination. 

Food arsenic values taken from FDA surveys indicate an average daily 
dietary intake of approximately 50 pg arsenic (Johnson et al., 1984; Gartrell et 
al., 1985; U.S. EPA, 1984 a,b). Generally, the meat, fish, and poultry 
composite group is the predominant source of arsenic intake for adults and 
has been estimated to account for about 80% of arsenic intake (Gartrell et al., 
1985; Hummel, 1986; 1987; U.S. EPA, 1984b). Of this composite group, fish 


101 


and seafood consistently contain the highest concentrations of arsenic. The 
concentration of arsenic in fish and seafood (particularly shell fish and marine 
foods) is generally one to two orders of magnitude higher than that in other 
foods (FDA, 1985; Jelinek and Corneliussen, 1977). The second most 
concentrated source of arsenic in these FDA surveys is the grain and cereal 
group which may account for about 17% of arsenic. Following these groups 
are vegetables, sugars, oils, fats, and beverages. In the average U.S. adult 
diet, dairy products account for 26% by weight; meat, fish, and poultry 9%; 
grain and cereal products 14%; potatoes 5%; fruits 11%; and vegetables 6% 
(Gartrell et al., 1985). 

An analysis of arsenic species in foods sampled by the Canadian 
government shows that most of the arsenic in meats, poultry, dairy products, 
and cereals is inorganic (Weiler, 1987). Fruits, vegetables, and fish contain 
arsenic predominantly in organic forms. These data, though based on a 
limited number of samples, are included here (Table E-1) because, until 
recently, this type of breakdown by arsenic species has not been available. 

Table E~1. Percentage of Inorganic 
Arsenic in Food: A 
Preliminary Analysis^ 


Food 

Percentage of 
Inorganic Arsenic 

Milk and dairy products 

75 

Meat - beef and pork 

75 

Poultry 

65 

Fish - saltwater 

0 

- freshwater 

10 

Cereals 

65 

Rice 

35 

Vegetables 

5 

Potatoes 

10 

Fruits 

10 


^Speciation of the arsenic content of basic food 
groups based on preliminary data from the Ontario 
Research Foundation and other sources. 

SOURCE: Weiler, 1987. 

Because of the very large quantities of arsenic in fish and seafood, many 
investigators have studied the chemical forms of arsenic in fish and their 
metabolism, excretion, and toxicity in humans. As noted in Table E-1, 
arsenic in seafood is predominantly organic. A number of researchers have 
shown that these organic forms are trimethylated. In 1977, Edmonds et al. 
showed that rock lobster contained 26 ppm of arsenic as arsenobetaine, 
(CH 3)3 As‘^CH 2 CO 2 . Other researchers have shown that trimethyl arsenic in 
fish also occurs in other chemical structures, such as arsenocholine. 


102 




Yamauchi and Yannamura (1984) showed that although most of the trimethyl 
arsenic compounds in prawns were excreted unchanged, 3% to 5% is 
changed to mono- and dimethylated forms or to inorganic arsenic. Thus, 
although most of the organic arsenic in seafood is excreted rapidly and 
unchanged, some of it may be retained in the soft tissues, undergo 
biotransformation, and be available biologically. 

D. Occupationally Exposed Groups 

Pesticide applicators and workers in copper, lead, and zinc smelters, glass 
manufacturing plants, chemical plants, wood preserving plants, and cotton 
gins are exposed to high levels of arsenic. Smelter workers are exposed to 
trivalent arsenic, workers in wood preserving plants are exposed to 
pentavalent arsenic, and pesticide applicators are exposed to various 
inorganic salts as well as mono-methyl arsenic (MMA) and cacodylic acid or 
dimethyl arsenic (DMA). 

The OSHA standard is 10 ng arsenic/m^ (8-hour time-weighted average) 
for industrial exposure (OSHA, 1986). Using the previous assumption for daily 
ventilation rate and lung absorption and assuming an 8-hour workday, an 
occupationally exposed person could receive about 80 iig corresponding to 
68 ^ig water-soluble arsenic absorbed daily via inhalation at the OSHA 
standard. Because arsenic is poorly absorbed dermally (approximately 0.1%), 
dermal exposure has been considered to be negligible as compared to 
inhalation exposure. 

E. Total Daily Body Burden 

Table E-2 represents the range of total body burden of arsenic from all 
sources: dietary, drinking water, smoking, ambient air, and occupational 
exposure, in the United States, namely 55.09 to 224 pg/day. As noted in this 
section, water and air generally contain arsenic in Inorganic and organic 
forms. Using information about the percentages of inorganic arsenic in various 
food groups, combined with FDA surveillance data on the contributions of 
these foods to the daily arsenic intake, it appears that the diet including 
drinking water and beverages contains about 17 or 18 ng/day of inorganic 
arsenic (Table E-2). 

III. Metabolism, Bioavailability, and Toxicity 

A. Toxicity of Arsenic Chemical Species 

Chronic arsenic intoxication can lead to gastrointestinal disturbances, 
hyperpigmentation, and peripheral neuropathy (Goyer, 1986^ Arsenic is also 
carcinogenic, and Jacobson-Kram (1986) notes that arsenic is clastogenic 
and causes sister chromatic exchange. 

The toxicity of arsenic is closely related to its chemical form. Inorganic 
salts and acids of arsenic occur predominantly in the tri- and pentavalent 
oxidation states. It is well known from acute exposure studies that trivalent 
arsenic is more toxic than pentavalent arsenic (Goyer, 1986). Recent studies 
have shown that at environmental levels, pentavalent arsenic is rapidly 
converted to trivalent arsenic in the blood (Marafante et al., 1985). These two 
forms can be readily interconverted in mammals. Trivalent and pentavalent 
arsenic salts also have different modes of toxic action. Cellular mechanisms 
of arsenic toxicity have been discussed in several current reviews (Goyer, 
1986; Vahter and Marafante, 1983). For example, Vahter and Marafante note 
that "Arsenite is known to react with SH-groups of proteins and enzymes 


103 


Table E-2. Daily Arsenic Body 

Burden (pg/day) in the 
United States 


Source 

Usual 

Unusual 

Water 

5 

100a 

Air 

0.09 

1.5 - 45 b 

\ 


68C 

Food 

50d 

50 

Smoking 


2 - 66 

TOTAL 

55.09 

up to 224 


aAt the ODW maximum containment level 
(see Part II.A). 

hNear industrial use sites such as smelter or 
cotton gins (see Part II.B). 

^Occupational exposure. 
dSee Part II.C. 

62 pg arsenic/package (Weiler, 1987; 
lARC, 1986). 


while arsenate may interfere with phosphorylation reactions due to its 
chemical similarity with phosphate." 

Methylation of inorganic salts of arsenic through the trivalent state appears 
to be a detoxification pathway in mammals (Vahter, 1983). The simple 
methylated forms of arsenic, namely cacodylic acid and methanearsonate, are 
less acutely toxic than the inorganic salts. Fairchild et al. (1977) gives the 
LD 50 of arsenic trioxide as 1.43 mg/kg. of MMA as 50 mg/kg, and of DMA as 
500 mg/kg. Trimethylated forms of arsenic are not acutely toxic and are 
rapidly excreted (Vahter, 1983). Although tested in animals, the oncogenic 
potential of the organic forms has not been adequately characterized. 

B. Absorption, Distribution, and Elimination 

Arsenic exposure occurs predominantly through ingestion and inhalation. 
Dermal absorption is negligible. A detailed understanding of the mammalian 
distribution, elimination, and long-term deposition patterns following 
exposure and the relationship of these processes to the internal body burden 
can provide insights into tissue sites for chronic target organ toxicity. 

In smelters, inhaled arsenic and that brought to the gastrointestinal tract by 
mucociliary clearance, leads to approximately 80% absorption (Pershagen 
and Vahter, 1979). Smith et al. (1977) showed that nonrespirable particulate 
forms of arsenic were more closely correlated with excretion of arsenic than 
respirable forms. These results imply that ingested forms of arsenic are better 
absorbed and get into the bloodstream more efficiently than inhaled arsenic. 
Marafante and Vahter (1987) compared absorption and tissue retention of 
arsenic salts administered orally and intratracheally in the hamster. In general, 
orally administered arsenic had a shorter biological half-life than that 
administered intratracheally. Clearance of arsenic compounds from the lungs 
was also closely correlated with solubility under physiological conditions. 


104 




Brune et al. (1980) collected autopsy specimens from a group of 21 
Swedish smelter workers employed between 10 and 30 years in a smelter. A 
control group consisted of eight individuals from a region 50 km from the 
smelter site. Arsenic levels in kidney and liver were comparable for workers 
and control subjects, but levels of arsenic in lung tissue were about 6 times 
higher for the smelter workers than the control group. Furthermore, arsenic 
levels in the lungs of workers retired up to 19 years were comparable to those 
in workers autopsied less then 2 years after retirement. However, if smoking 
is a factor, the high lung levels in some subjects may be a function of chronic 
exposure to arsenic in tobacco smoke. For example, Vahter (1986) reports 
that some smokers in the 1950s may have inhaled as much as 0.1 ^ig arsenic 
each day. Although the complete smoking history of these workers is not 
known and the duration of exposure of the two groups of retirees is not 
completely defined, the Brune et al. study may indicate that a portion of 
inhaled arsenic binds irreversibly to lung tissue. 

Valentine et al. (1979) measured arsenic levels in human blood, urine, and 
hair in five United States communities with arsenic concentrations in drinking 
water ranging from 6 pg/L to 393 pg/L. Their results showed that arsenic 
concentrations increased in urine and hair samples in proportion to increases 
in concentrations in drinking water. However, this trend was not reflected in 
blood until drinking water concentrations exceeded 100 pg/L. 

Various researchers have monitored arsenic excretion in the urine and the 
feces and found that the urinary tract is the major route of elimination and 
accounts for more than 75% of absorbed arsenic over time. Animal studies 
have also shown that little, if any, absorbed arsenic is exhaled (WHO, 1981). 
Thus, since the late 1970s, pharmacokinetic and metabolism studies have 
monitored the urine alone as an approximate surrogate for excretion. When 
organic arsenic is administered orally, it is eliminated more rapidly than 
inorganic forms. In addition to urine and feces, arsenic is also eliminated from 
the body via sweating and desquamation of the skin. In humans not 
excessively exposed to inorganic arsenic, the highest tissue concentration of 
arsenic is generally found in skin, hair, and nails (Liebscher and Smith, 1968). 
Kagey et al. (1977) also studied women In the United States and showed that 
umbilical cord levels of arsenic were similar to maternal levels. 

Because of the limitations of human studies of absorption, elimination, and 
tissue distribution of arsenic, various researchers have used the recent 
advances in arsenic speciation methods to study the way laboratory animals 
handle arsenic. Lindgren et al. (1982) injected mice with radiolabeled 
(inorganic) arsenic and used whole body radiography to study its distribution 
and clearance. Initial concentrations were highest in the bile and kidney for 
arsenate, but clearance from these tissues was extremely rapid. After 72 
hours, the highest concentrations were in the epididymus, hair, skin, and 
stomach for arsenite and the skeleton, stomach, kidneys, and epididymus for 
arsenate. Arsenate was cleared more rapidly than arsenite from all soft 
tissues but the kidneys. It seems probable that this pattern of uptake is 
related to the chemical similarities between arsenate and phosphate in the 
apatite crystals in bone. One can ascribe the accumulation of arsenic in skin, 
hair, and upper gastrointestinal tract to its binding of sulfhydryl groups of 
keratin (Goyer, 1986). 

Following intravenous injection of DMA in rabbits or mice, excretion was 
essentially complete within 24 hours, indicating low affinity for the tissues in 
vivo (Vahter and Marafante, 1983). The same results were obtained following 
oral administration (Vahter et al., 1984). In addition, the distribution showed a 
different pattern from that shown after administration of inorganic arsenic, as 


105 


discussed above. The highest initial concentration of arsenic in mice was 
found in the kidneys, lungs, gastrointestinal tract, and testes. Tissues showing 
the longest retention time were the lungs, thyroid, intestinal walls, and lens. 

Tissue retention of arsenic in the marmoset monkey, which doesn’t 
methylate arsenic, was much more pronounced than in species which 
methylate arsenic (Vahter and Marafante, 1985). Seventy-two hours after 
injection with inorganic arsenic, almost 60% was still bound to the tissues. 
The major single binding site was liver, with 10% of the original dose. Arsenic 
was also retained in the kidney and gastrointestinal tract. To the extent that 
the marmoset monkey may be an appropriate model of distribution and tissue 
retention in humans when arsenic levels exceed the normal detoxification 
capacity, these studies may enable us to predict accumulation of arsenic in 
the liver, kidney, and gastrointestinal tract from chronic high exposure. 

In summary, systematic animal studies and observations in humans show 
that arsenic is efficiently absorbed through the gastrointestinal tract and via 
inhalation and eliminated predominantly in the urine. High levels of exposure 
can lead to deposition in tissues rich in sulfhydryl (SH) groups such as the 
lung tissue, gastrointestinal tract, skin, and hair. Arsenic also appears to 
concentrate in the liver and to a lesser extent the kidney, especially in the 
marmoset monkey which does not methylate arsenic. As discussed above, 
the chemical form of arsenic influences its retention time and target tissue 
sites. 

C. Detoxification Via Methylation 

Methylation of inorganic arsenic is generally accepted as a detoxification 
mechanism of mammals. Vahter (1983) and Vahter et al. (1984) showed that 
methylated arsenic is excreted more rapidly after ingestion than the inorganic 
forms. In addition, cumulative observations of humans acutely exposed to 
inorganic arsenic show that, although inorganic arsenic is the predominant 
initial metabolite, after 9 days, MMA and DMA account for more than 95% of 
total arsenic excreted in the urine (Mahieu et al., 1981). Various researchers 
have shown that methylation of inorganic arsenic occurs enzymatically prior 
to elimination in the urine. The enzymatic pathways for arsenic methylation 
and detoxification are summarized in this section. 

Methylation appears to take place through the trivalent As (+ 3) state 
(Vahter and Envall, 1983). Based on studies with model compounds, Cullen et 
al. (1984) hypothesized that methylation of arsenic III requires s- 
adenosylmethionine in excess, dithiollpoic acid-like structures on the 
membranes, and/or a functional enzyme system (see Figures E-1 and E-2). 

The major site of methylation appears to be the liver (Klaassen, 1974). 
Lerman et al. (1985) followed methylation of tri- and pentavalent arsenic in 
cultures of hepatocytes. They found that dimethyl arsenic acid formed when 
arsenite, but not arsenate, was added to the culture medium. No metabolism 
of arsenate was seen, nor was the arsenate taken up by the liver cells. The 
authors postulated that the differences in in vitro cellular uptake of the two 
forms of arsenic may be due to the fact that, at physiologic pH, arsenite is not 
ionized, whereas arsenate is charged. 

In order to understand reaction mechanisms and sequences of 
methylation, Buchet and Lauwerys (1985) performed in vitro incubations of 
inorganic arsenic with various (rat) tissues. The methylating capacity of red 
blood cells, and brain, lung, intestine, and kidney homogenates were 
insignificant by comparison to that of the liver. They found that the cytosol 
was the sole fraction of the liver showing methylating activity: and s- 


106 


Figure E-1. 


Reproduction of arsenic III forms by membrane-bound lypoic acid. 
Source: Cullen et al., 1984. 




Figure E-2. Role of s-adenosylmethionine in methylation of arsenic III. 
Source: Cullen et al., 1 984. 


S-Adenosyl methionine 


S-Adenosyl homocysteine 




adenosylethionine and reduced glutathione were required as methyl donors. 
The effect was further enhanced by addition of vitamin B 12 to this system. 
Although MMA was formed immediately, a 30-minute latency period 
occurred before DMA was produced, suggesting that it is formed from MMA. 
As cytosol and subtrate (As +3) concentrations were varied, MMA and DMA 
appeared to exhibit different kinetics of formation. At high substrate 
concentrations, DMA formation was inhibited, while MMA appeared to 


107 




accumulate in the system, showing that formation of DMA is a rate-limiting 
step. 

Methyl transferase activity has been shown to play a necessary role in the 
methylation of arsenic in mammals (Marafante and Vahter, 1984, 1986; 
Marafante et al., 1985). The effect of dietary deficiencies and genetic 
variability on methylating capacity (shown below) has important implications 
for tissue distribution and individual susceptibility to arsenic toxicity. 

Marafante and Vahter (1984) studied the effect of methyl transferase 
inhibition on the metabolism and tissue retention of arsenite in mice and 
rabbits. Periodate-oxidized adenosine (PAD), an inhibitor of methyl 
transferase, was injected into mice and rabbits prior to administration of the 
arsenite. This led to a marked decrease in production of cacodylic acid, a 
dimethylated form of arsenic. Moreover, impairment of methylation increased 
the tissue retention of arsenic. These results imply that S-adenosyl- 
methionine is a methyl donor in the methylation of inorganic arsenic \n vivo 
and are consistent with the conclusions of Buchet and Lauwerys (1985) 
regarding the significance of various cofactors in vitro. 

In 1985, Marafante et al. measured blood as well as urinary concentrations 
of arsenic metabolites following the administration of arsenate. The reduction 
of arsenate to arsenite occurred almost immediately, followed by the 
appearance of DMA in the blood plasma after about an hour. The 
administration of PAD led to a dramatic decrease in the appearance of DMA 
in the blood and confirmed the earlier results in the laboratory showing the 
significance of methyl transferase activity in the methylative metabolism of 
arsenic. Urinary excretion of arsenate and its metabolites paralleled their 
concentrations in the blood. In light of these observations, these authors 
postulated that reduction of arsenate to arsenite is an initial and independent 
reaction in the biotransformation of arsenate and probably occurs in the 
blood. 

In a later study, Marafante and Vahter (1986) studied the effect of choline- 
deficient diets on the metabolism of arsenic in rabbits. Shivapurkar and Poirier 
(1983) had previously demonstrated that choline- or protein-deficient diets 
increase relative hepatic concentrations of s-adenosylhomocysteine, leading 
to inhibition of methyl transferase activity. In their study, Marafante and Vahter 
showed that both the choline-deficient diets and the administration of PAD 
led to decreased excretion of DMA in the urine and higher retention of "^^As in 
the liver, lungs, and skin. (As noted above, this pattern is seen in the 
marmoset monkey which lacks the genetic capacity to methylate arsenic.) In 
addition, choline deficiencies led to an increased concentration of ^'^As in the 
liver microsomes. 

These observations demonstrate that methylation as a detoxification 
pathway is enzymatic and occurs via the trivalent state of arsenic to MMA and 
subsequently to DMA. Furthermore, decreased methylating capacity caused 
by chemical inhibition, dietary deprivation, or genetic disposition appears to 
lead to decreased excretion of DMA in the urine, with retention of arsenic in 
the lungs, skin, and liver. In addition, certain dietary deficiencies lead to 
concentration of arsenic in the liver microsomes. These results In animals 
may be considered to mimic that segment of the human population described 
as poor methylators. [See the following section for a summary of the human 
studies by Foa et al. (1984) and Buchet et al. (1982).] They may also serve as 
models for those populations consuming protein-deficient diets while 
exposed to high levels of arsenic. In these populations, one can anticipate that 
decreased methylating capacity can lead to an increased deposition of 


108 


arsenic in liver and lung cells as well as the organ sites of normal distribution, 
namely skin, hair, and nails. 

D. Human Metabolism and Enzyme Kinetics 

This section contains summaries of human studies of the metabolism and 
enzyme kinetics of arsenic. In these studies, dosing or exposure levels 
ranged from background levels to which the general population is normally 
exposed, through levels representing occupational exposure, up to highly 
toxic levels. The dosing patterns include acute, short-term, and chronic 
exposure. Of necessity, many of these studies are limited to single doses in 
small numbers of human volunteers. Nonetheless, when seen in the context 
of the enzyme kinetics of arsenic methylation described previously, they 
provide valuable insights into the way humans can handle, detoxify, and 
eliminate arsenic at levels of concern. 

Buchet et al. (1981) performed a series of pharmacokinetic studies of 
arsenic metabolism in human volunteers exposed to levels of arsenic roughly 
comparable to those in smelters. In the first study, groups of three, four, or 
five adult males drank solutions containing 500 tig equivalents of inorganic 
arsenic, MMA, or DMA. After a single dose, urine was collected for four days 
and analyzed for inorganic arsenic, MMA, or DMA. In four days, total or 
cumulative arsenic content as monitored by urinary excretion, amounted to 
about 47% of the ingested dose of inorganic arsenic, 78% of ingested MMA, 
and 75% of ingested DMA, indicating much more rapid excretion of organic 
than inorganic forms. After ingestion of inorganic arsenic, the percentage of 
inorganic arsenic excreted in the urine fell off extremely rapidly and was 
accompanied by an increase of DMA excretion. However, MMA excretion 
initially increased and then at 12 to 24 hours began to decrease. When MMA 
was ingested, MMA accounted for 87.4% and DMA accounted for 12.6% of 
urinary arsenic after 4 days indicating some bioconversion of MMA to DMA, 
but no demethylation. When DMA was ingested, all urinary arsenic was 
excreted as DMA. These observations, in light of the relative toxicities of the 
metabolites, demonstrate that methylation is an efficient detoxification 
pathway for arsenic. 

In a second human study, Buchet et al. (1982) studied urinary metabolites 
after repeated oral dosing for 5 days with 125, 250, 500, or 1,000 ng inorganic 
arsenic. In this study, urinary monitoring was performed for 9 days following 
the last dose. Although only one volunteer was tested at each dose, they were 
chosen in the context of previous studies in the laboratory to have normal 
methylation rates. Above 500 \ig the ratio of DMA to MMA decreased and 
methylating capacity appeared to fall off as shown in Figure E-3. When the 
percentage of each metabolite was plotted against the log of the ingested 
dose, the concentration (percentage) of inorganic arsenic declined and that of 
DMA increased commensurate with first-order kinetics. The rate of 
conversion to methylated forms diminished starting at 250 pg, but not until the 
dose range exceeded 500 iig did the absolute amount of DMA decline 
indicating saturation of methylating capacity. In addition, the biological half- 
life of total recovered arsenic increased with increasing dose (39 h at 125 ng 
to 59 h at 1000 ng). The authors indicated that when they saw these results, 
they re-examined the history of the high-dose volunteer, but confirmed that 
his excretion pattern for arsenic was not out of line with the others. These 
results suggest the hypothesis that saturation of methylating capacity occurs 
just above 500 pg/day in healthy adult males exposed to repeated doses of 
arsenic in short-term experiments. However, confirmation of the enzyme 


109 


Figure E-3. 


Urinary concentrations of arsenic and its metabolites. 
Source: Adapted fromBuchet et al., 1 982, 



saturation pattern would require that EPA obtain the raw data fronn Buchet’s 
experiments. 

These short-term dose-response curves are typical of enzymatic 
conversion processes. Buchet’s studies include a dosing range up through 
enzymatic saturation and beyond it. At about 600 pg/day the absolute amount 
of MMA begins to plateau, and the saturation of methylation occurs between 
doses of 500 and 1,000 pg/day in people of adequate methylating capacity 
(Figure E-3). 

In 1985, Lovell and Farmer monitored urine for arsenic metabolites 
following ingestion of highly toxic doses of inorganic arsenic by people 
attempting suicide. In the course of 5 days, a decreasing percentage of 
inorganic arsenic was eliminated with a corresponding increasing percentage 
of DMA, implying metabolic conversion of one to the other. The amount of 
MMA in the urine did not show any such clear pattern. A similar pattern of 
urinary metabolites to that observed by Lovell and Farmer (1985) as well as 
Buchet et al. (1981) was seen by Tam et al. (1979) (Figure E-4). 

From the dose-response experiments and the time course of elimination, 
one can postulate that after the initial rapid excretion of inorganic arsenic 
arising from ingestion of inorganic arsenic, simple enzymatic conversion to 


110 























As Radioactivity uC\ 


Figure E-4. 


Excretion of arsenic metabolites following a single oral dose of 
inorganic arsenic. ^'’As radioactivity in urine of male volunteer No 
5; ingested dose: 6.45 /yCi. 

Source: Tam et al., 1 979. 



Day 



Total arsenic 
Inorganic arsenic 
Monomethylarsenic compound 


Dimethylarsinic acid 


111 





DMA, first order in the inorganic arsenic substrate, occurs in the liver. The 
DMA is then excreted via the kidneys. However, conversion of arsenic to 
MMA as observed by urinary excretion does not indicate simple kinetics. 
Possibly, this conversion occurs at the cellular level throughout the body, or 
by nonenzymatic mechanisms. In light of this elimination pattern for short¬ 
term experiments, conversion of inorganic arsenic to DMA appears to be the 
rate-limiting step in detoxification (Buchet and Lauwerys, 1985). 

Foa et al. (1984) measured blood and urinary metabolites of arsenic in 40 
glass workers exposed to high levels of arsenic and in 148 control subjects 
drawn from the general population. These researchers found a broad range 
and standard deviation for each metabolite in the blood and urine. Perhaps 
the most significant finding in this study was that, although many of the 
subjects were good methylators, each group contained subjects with clearly 
reduced methylation capacity as seen by the profile of metabolites. For the 
glass workers, both blood and urine concentrations of total arsenic were 
increased in proportion to the exposure, although metabolite profiles were 
comparable. 

Foa et al. (1984) also selected a group of five glass workers with high 
urinary arsenic concentrations and suspended their exposure for one month. 
Urinary concentrations of arsenic and its methylated metabolites decreased 
with time nearly to that of the control population. However, when high 
exposure was resumed, only a moderate increase was seen for inorganic 
arsenic and its methylated metabolites. Two months after exposure resumed, 
urinary concentrations of total arsenic were still diminished relative to daily 
exposure (Figure E-5). Furthermore, day-to-day and morning-to- 
evening sampling showed only the slightest variation in concentration of 
inorganic arsenic, with no variation in concentration of its methylated 
metabolites. This appears to indicate that full methylation capacity for high 
exposures takes several months to build up and that any accommodation the 
body had made to very high arsenic levels is rapidly lost. Comparing their 
observations with human studies in other laboratories, these researchers 
postulated that the time course of excretion of metabolites indicates a 
saturable mechanism for the methylation of arsenic. 

In a very recent study, Vahter (1986) compared urinary arsenic metabolites 
in smelter workers having high chronic exposures to those in a general 
population of non-fish eaters in Sweden. The profile of metabolites was 
strikingly similar (Inorganic arsenic;MMA:DMA was 18%:16%:65% and 
19%:20%:61%, respectively) and implied the occurrence of long-term 
accommodation to high levels of arsenic by the smelter workers. 

In summary, similar patterns of enzymatic methylation have been 
demonstrated in both animals and humans. Short-term studies demonstrate 
that these enzymatic detoxification pathways are saturable as noted above. 
However, the human studies demonstrate a long-term accommodation 
pattern such that occupationally exposed people eliminate inorganic arsenic, 
MMA, and DMA in the same relative proportions as the general population or 
lightly exposed worker groups. Although the pattern of accommodation is 
consistent with traditional clinical observations of arsenic toxicology, the panel 
could not find any research that would enable the mechanism of 
accommodation to be elucidated. Finally, a number of researchers observed 
that methylation capacities In large populations can be highly variable. 


112 


As (/ig/L) 


Figure E-5. Urinary excretion of arsenic (As) and its metabolites in glass workers 
with prolonged exposure to arsenic trioxide, after suspension and 
resumption of exposure. Values are means ±SD of five subjects. 
Source: Foa et al., 1984. 



Months 


IV. Pharmacokinetics of Arsenic Metabolism and Its Implications 
for Oncogenicity 

Although most forms of arsenic to which people are commonly exposed 
are biologically available, inorganic arsenic is the most toxic. Inorganic arsenic 
is methylated enzymatically in the liver prior to its elimination in the urine. 
When the methylation capacity of the liver is exceeded, exposure to excess 
levels of inorganic arsenic can lead to increased and long-term deposition in 
certain target tissues, namely the liver, lung, skin, bladder, and 
gastrointestinal tract. 

One can speculate that the methylation capacity may be exceeded at 
lower levels of arsenic exposure in the segments of the human population that 
are poor methylators due to genetic disposition or in groups consuming poor 
or protein- deficient diets. This may explain the anomalies noted by 


113 








Enterline in the manifestation of carcinogenic response in epidemiological 
studies of certain highly exposed groups (U.S. ERA, 1987). 

Long-term accommodation to arsenic (on the order of several months or 
more) appears to take place in occupationally exposed worker populations as 
demonstrated by similar profiles of arsenic metabolites in the urine over a 
wide range of exposures. However, blood levels from high chronic exposure 
to arsenic (in excess of 200 ng/day) indicate that the accommodation may not 
be complete. However, even if the human body accommodates to chronically 
elevated arsenic levels, the internal tissues are nonetheless exposed to much 
more inorganic arsenic over long periods of time. Furthermore, the ability of 
the human organism to handle more than 500 or 600 ^lg/day may constitute a 
stress to the body. An improved understanding of these homeostatic 
mechanisms is critical to improving the cancer dose-response assessment. 

Appendix C summarizes data on elevated rates of cancer of the liver, lung, 
and bladder in Taiwan and also notes the occurrence of internal tumors in the 
Fierz study. Extrapolating from the studies on protein-deficient animals, one 
would expect liver cancer to be especially prevalant in protein-deficient 
human populations. Future work may show whether the deposition patterns 
are matched by confirmed incidence of internal cancer. 


114 


IX. References 


Albores, A.; Cebrian, M.E.; Tellez, 1.; Valdez, B. (1979) Comparative study of 
chronic hydroarsenicism in two rural communities in the lagoon region of 
Mexico. Bol. Of. Sanit. Panam. 86:196-203. 

Alvarado, L.C.; Viniegran, G.; Garcia, R.E.; Acevedo, J.A. (1964) Arsenicism in 
the lake region. An epidemiologic study of arsenicism in the colonies of 
Miguel-Aleman and Eduardo Guerra of Torreon, Coahvila (Mexico). 
Salud Publica Mex. Edition V 6(3):375-385. 

Andelman, J.B; Barnett, M. (1983) Feasibility study to resolve questions on 
the relationship of arsenic in drinking water to skin cancer. U.S. 
Environmental Protection Agency Cooperative Agreement No. CR- 
806815-02-1. 

Anderson, C.E. (1983) Arsenicals as feed additives for poultry and swine. In: 
Lederer, W.; Fensterheim, R., eds. Arsenic: industrial, biomedical, and 
environmental perspectives. New York, NY; Van Nostrand Reinhold, p. 
89. 

Anke, M.; Grun, M.; Partschefeld, M. (1976) The essentiality of arsenic for 
animals. \n: Hemphill, D.D., ed. Trace substances in environmental health, 
Vol. 10. University of Missouri, Columbia, Missouri, pp. 403-409. 

Anke, M.; Grun, M.; Partschefeld, M.; Groppel, B.; Hennig, A. (1978) 
Essentiality and function of arsenic. In: Kirchgessner, M., ed. Trace 
element metabolism in man and animals, Vol. 3. Freising- 
Weihenstephen Tech. University, Munich, pp. 248-252. 

Arguello, A.; Cenget, D.; Tello, E. (1938) Regional endemic cancer and 
arsenical intoxication in Cordoba. Argentine Review of 
Dermatosyphilology, Vol. XXII, Pt. 4. Presented at the 6th National 
Medical Congress, Cordoba, October 16-21, 1938. 

Armitage, P. (1982) The assessment of low-dose carcinogenicity. Biometrics 
Supplement: Current topics in biostatistics and epidemiology, pp. 119- 
129. 

Armitage, P.; Doll, R. (1954) The age distribution of cancer and a multistage 
theory of carcinogenesis. Br. J. Cancer 8:1-13. 

Astrup, P. (1968) Blackfoot disease. Ugeskr. Laeger 130:1807-1815. 

Bergoglio, R.M. (1964) Mortality from cancer in regions of arsenical waters of 
the province of Cordoba, Argentine Republic. Pren. Med. Argent. 51: 
994-998. 

Biagini, R.E. (1972) Chronic hydroarsenism and death from malignant 
cancers. La Semana Medica, 25:812-816. 

Biagini, R.E. (1974) Present considerations on endemic chronic regional 
hydroarsenism. La Semana Medica 145:716-723. 

Biagini, R.E.; Castoldl, F.; Vazques, C.A.; Farjat, R.E. (1972) Chronic 
hydroarsenism and leucoplasia. Archives Argentines de Dermatologia, 
22(1,2): 53-58. 


115 


Biagini, R.E.; Quiroga, G.C.; Elias, V. (1974) Chronic hydroarsenism in ururau. 
Archives Agentinos de Dermatologia 24(1):8-11. 

Biagini, R.E.; Rivero, M.; Salvador, M.; Cordoba, S. (1978) Chronic arsenisnn 
and lung cancer. Archives Argentines de Dermatologia 48:151-158. 

Birmingham, D.J.; Key, M.M.; Holaday, D.A.; Perone, V.B. (1965) An outbreak 
of arsenical dermatoses in a mining community. Arch Dermatol. 91:457- 
464. 

Borgono, J.M.; Greiber, R. (1972) Epidemiological study of arsenicism in the 
city of Antofogasta. In: Trace substances in environmental health, V: 
Proceedings of the University of Missouri’s 5th annual conference on 
trace substances in environmental health. June 29-July 1, 1971. In 
Columbia, MO. Rev. Med. Chil. 9:702-701. 

Borgono, J.M.; Vincent, P.; Venturino, H.; Infante, A. (1977) Arsenic in the 
drinking water of the city of Antofogasta: epidemiological and clinical 
study before and after the installation of the treatment plant. Environ. 
Health Perspect. 19:103-105. 

Borgono, J.M.; Venturino, H.; Vincent, P. (1980) Clinical and epidemiological 
study of arsenicism in northern Chile. Rev. Med. Chil. 108:1039-1048. 

Boutwell, R.K. (1983) Diet and anticarcinogens in the mouse skin two-stage 
model. Cancer Res. (Suppl.) 43:2465s-2468s. 

Braun, W. (1958) Carcinoma of the skin and the internal organs caused by 
arsenic: delayed occupational lesions due to arsenic. German Med. 
Monthly 3:321-324. 

Brune, D.; Nordberg, G.; Wester, P. (1980) Distribution of 23 elements in the 
kidney, liver, and lungs of workers from a smelter and refinery in North 
Sweden exposed to a number of elements and of a control group. Sci. 
Total Environ. 16:13-35. 

Buchet, J.P.; Lauwerys, R. (1985) Study of inorganic arsenic methylation by 
rat liver in vitro: Relevance for the interpretation of observations in man. 
Arch. Toxicol. 57:125-129. 

Buchet, J.P.; Lauwerys, R.; Reels, H. (1981) Comparison of the urinary 
excretion of arsenic metabolites after a single oral dose of sodium 
arsenite, monomethylarsonate or dimethylarsinate. Int. Arch. Occup. 
Environ. Health 48:71-79. 

Buchet, J.P.; Lauwerys, R.; Mahieu, P.; Geubel, A. (1982) Inorganic arsenic 
metabolism in man. Arch. Toxicol. Suppl. 5:326-327. 

Calnan, C.D. (1954) Arsenical keratoses and epitheliomas with bronchial 
carcinoma. Proc. R. Soc. Med. 47:405-406. 

Cebrian, M.E. (1987) Risk Assessment Forum Workshop on arsenic. 
Summary report of a workshop held in December 1986. Available from: 
U.S. EPA Headquarters Library, Washington, D.C. 

Cebrian, M.E.; Albores, A.; Aquilar, M.; Blakely, E. (1983) Chronic arsenic 
poisoning in the north of Mexico. Human Toxicol. 2:121-133. 

Chavez, A.; Perez Hidalgo, C.; Tovar, E.; Garmilla, M. (1964) Studies in a 
community with chronic endemic arsenic poisoning. Salud Publica Mex 
6(3):435-442. 

Chen, C.J. (1987) Risk Assessment Forum Workshop on arsenic. Summary 
report of a workshop held in December 1986. Available from: U.S. EPA 
Headquarters Library, Washington, D.C. 


116 


Chen, C.J.; Chuang, Y.C.; Lin, T.M.; Wu, H.-Y. (1985) Malignant neoplasms 
among residents of a Blackfoot disease-endemic area in Taiwan: high- 
arsenic artesian well water and cancers. Cancer Res. 45:5895-5899. 

Chen, C.J.; Chuang, Y.C.; You, S.L.; Lin, T.M.; Wu, H.Y. (1986) A retrospective 
study on malignant neoplasms of bladder, lung, and liver in Blackfoot 
disease endemic area in Taiwan. Br. J. Cancer 53:399-405. 

Ch’i, I.C.; Blackwell, R.Q. (1968) A controlled retrospective study of Blackfoot 
disease and epidemic peripheral gangrene disease in Taiwan. Am. J. 
Epidemiol. 88:7-24. 

Cornatzer, W.E.; Uthus, E.O.; Haning, J.A.; Nielsen, F.H. (1983) Effect of 
arsenic deprivation on phosphatidyl choline biosynthesis in liver 
microsomes on the rat. Nutr. Reports. Mtl. 27(4):821-829. 

Crossen, P.E. (1983) Arsenic and SCE in human lymphocytes. Mutat. Res. 
119: 415-419. 

Cullen, W.R.; McBride, B.C.; Reglinski, J. (1984) The reduction of 
trimethylarsine oxide to trimethylarsine by thiols: a mechanistic model for 
the biological reduction of arsenicals. J. Inorg. Biochem. 21:45-60. 

Cuzik, J.; Evans, S.; Gillman, M.; Price Evans, D. (1982) Medicinal arsenic and 
internal malignancies. Br. J. Cancer 45:904-911. 

Dean, B.J. (1978) Genetic toxicology of benzene, toluene, xylenes and 
phenols. Mutat. Res. 47:75-97. 

Edmonds, J.S.; Francisconi, K.A.; Cannon, J.R.; Raston, C.L.; Skelton, B.W.; 
White, A.FI. (1977) Isolation crystal structure and synthesis of 
arsenobetaine, the arsenical constituent of the western rock lobster. 
Tetrahedron Letters 13:1543-1546. 

Enterline, P.E.; Marsh, G.M. (1980) Mortality studies of smelter workers. Am. 
J. Ind. Med. 1:251-259. 

Fairchild, E.J.; Lewis, R.J.; Tatken, R.L. (1977) Registry of toxic effects of 
chemical substances. U.S. Department of Flealth Education and Welfare, 
National Institute of Occupational Safety and Health, Cincinnati, Ohio. 

Falk, H.; Caldwell, G.G; Ishak, K.G.; Thomas, L.B.; Popper, H. (1981) Arsenic 
related hepatic angiosarcoma. Am. J. Ind. Med. 2:43-50. 

Fierz, U. (1965) Catamnestic investigations of the side effects of therapy of 
skin diseases with inorganic arsenic. Dermatologica 131:41-58. 

Flessel, C.P. (1978) Metals as mutagens. In: Schrauzer, G.W., ed: Inorganic 
and nutritional aspects of cancer. New York, NY: Plenum Press, pp. 
117-128. 

Foa, V.; Colombi, A.; Maroni, M.; Buratti, M.; Calzaferri, G. (1984) The 
speciation of the chemical forms of arsenic in the biological monitoring of 
exposure to inorganic arsenic. Sci. Total Environ. 34:241-259. 

Food and Drug Administration (FDA), (1985) Unpublished data. Arsenic intake 
from individual foods in market baskets 1-8, 1982-1984. Available 
from: U.S. EPA Headquarters Library, Washington, D.C.) 

Fornace, A.J.; Little, J.B. (1979) DNA-protein cross-linking by chemical 
carcinogens in mammalian cells. Cancer Res. 39:704-710. 

Gartrell, M.J.; Craun, J.C.; Podrebarac, D.S.; Gunderson, E.L. (1985) Pesti¬ 
cides, selected elements, and other chemicals in adult total diet samples, 
October 1979-September 1980. J. Assoc. Off. Anal. Chem. 68:1184- 
1197. 


117 


Geyer, L. (1898) Uber die chronischen Hautveranderungen beim 
Arsenicismus und Betrachtungen uber die Masemerkrankungen in 
Reichenstein in Selesien. Arch. Dermatol. Syph. 43:221-283 (translated 
from German). 

Goyer, R.A. (1986) Toxic effects of metals - Chapter 19. In: Klaasen, C.D.; 
Amdur, M.O.; Doull, J., eds. Casarett & Doull’s Toxicology. New York, NY: 
Macmillan Publishing Co., pp. 582-635. 

Graham, J.H.; Helwig, E.B. (1963) Cutaneous precancerous conditions in man. 
Natl. Cancer Inst. Monogr. 10:323-333. 

Harrington, J.M.; Middaugh, J.P.r Morse, D.L.; Housworth, J. (1978) A survey 
of a population exposed to high concentrations of arsenic in well water in 
Fairbanks, Alaska. Am. J. Epidemiol. 108(5):377-385. 

Heydorn, K. (1970) Environmental variation of arsenic levels in human blood 
determined by neutron activation analysis. Clin. Chim. Acta 28:349-357. 

Hove, E.; Elvehjem, C.A.; Hart, E.B. (1938) Arsenic in the nutrition of the rat. 
Am. J. Physiol. 124:205-212. 

Hugo, N.E.; Conway, H. (1967) Bowen’s disease: its malignant potential and 
relationship to systemic cancer. Plast. Reconstr. Surg. 39:190-194. 

Hummel, S.B. (1986) Contribution by food to the body burdens of arsenic. 
Memorandum to A. Rispin (USEPA) January 30. Available from: U.S. EPA 
Headquarters Library, Washington, D.C. 

Hummel, S.B. (1987) Inorganic arsenic in the diet. Memorandum to A. Rispin 
(U.S. EPA) July 24. Available from: U.S. EPA Headquarters Library, 
Washington, D.C. 

Hutchinson, J. (1888) On some examples of arsenic keratoses of the skin and 
of arsenic cancer. Trans. Pathol. Soc. (London) 39:352-363 (as cited in 
Neubauer, 1947). 

International Agency for Research on Cancer. (lARC) (1976). Cancer 
incidence in five continents. Waterhouse, J.; Muir, G.; Correa, P.; Powell, 
J. Vol.3. 

International Agency for Research on Cancer. (lARC) (1986). lARC 
monograph on the evaluation of the carcinogenic risk of chemicals to 
man. Vol. 38. Tobacco smoking. Lyon, France: World Health 
Organization. 

Istvan, K.; Lujza, B.; Alajos, P; Kornel, B. (1984) Angiosarcoma of the liver 
after short-term arsenic therapy. Morphol. Igazsagugyi Orv. Sz. 
24:136-140. 

Jackson, R.; Gainge, J.W. (1975) Arsenic and cancer. Can. Med. Assoc. J. 
113(5):396-401. 

Jacobson-Kram, D. (1986) Use of genetic toxicology data in the evaluation of 
carcinogenic risk: inorganic arsenic. Unpublished draft. Available from: 
U.S. EPA Headquarters Library, Washington, D.C. 

Jacobson-Kram, D.; Montalbano, D. (1985) The Reproductive Effects 
Assessment Group’s report on the mutagenicity of inorganic arsenic. 
Environ. Mutagen. 7:787-804. 

Jelinek, C.F.; Corneliuessen, P.E. (1977) Levels of arsenic in the U.S. food 
supply. Environ. Health Perspect. 19:83-87. 

Johnson, R.D.; Manske, D.D.; New, D.H.; Podrebarac, D.S. (1984) Pesticide, 
metal, and other chemical residues in adult total diet samples. August 
1976 - September 1977. J. Assoc. Off. Anal. Chem. 67(1 ):154-166. 


118 


Jung, E.G.; Trachsel, B.; Imnnich, H. (1969) Arsenic as an inhibitor of the 
enzymes concerned in cellular recovery (dark repair). German Med. Mo. 
14:614-616. 

Kagey, B.T.; Bumgarner, J.E., Creason, J.P. (1977) Arsenic levels in 
maternal-fetal tissue sets. \n: Hemphill, D.D., ed. Trace substances in 
environmental health, XI. Proceedings of the University of Missouri’s 11 th 
annual conference on trace substances in environmental health, pp. 
252-256. 

Kelynack, T.N.; Kirkby, S.; Delepine, S. (1960) Arsenical poisoning from beer 
drinking. Lancet 2:1600-1603. 

Kjeldsberg, C.R.; Ward, H.P. (1972) Leukemia in arsenic poisoning. Ann. 
Intern. Med. 77:935-937. 

Klaassen, C.D. (1974) Biliary excretion of arsenic in rats, rabbits, and dogs. 
Toxicol. Appl. Pharmacol. 29:447-457. 

Knoth, W. (1966) Arsenbehandlung. Arch. Klin. Exp. Derm. 227:228-234. 

Lander, J.J.; Stanley, R.J.; Sumner, H.W.; Dee, C.; Boswell, D.C.; Arch, R.D. 
(1975) Angiosarcoma of the liver associated with Fowler’s solution 
(potassium arsenite). Gastroenterology 68:1582-1586. 

Lee-Feldstein, A. (1983) Arsenic and respiratory cancer in man: follow-up 
of an occupational study. In: Lederer, W.; Fensterheim, R., eds. Arsenic: 
industrial, biomedical, and environmental perspectives. New York, NY: 
Van Nostrand Reinhold, pp. 245-254. 

Leonard, A.; Lauwerys, R.R. (1980) Carcinogenicity, teratogenicity, and 
mutagenicity of arsenic. Mutat. Res. 75:49-62. 

Lerman, S.A.; Clarkson, T.W., Gerson, R.J. (1985) Arsenic uptake and 
metabolism by liver cells is dependent on arsenic oxidation state. Chem. 
Biol. Interact. 45:401-406. 

Liebegott, L. (1952) Relationships between chronic arsenical poisoning and 
malignant neoplasms. ZbI. Arbeitsmed. 2:15-16. 

Liebscher, K.; Smith, H. (1968) Essential and nonessential trace elements. A 
method of determining whether an element Is essential or nonessential in 
human tissue. Arch. Environ. Health 17:881-890. 

Lin, R.S. (1987) Risk Assessment Forum workshop on arsenic. Summary 
report of a workshop held in December 1986. (Available from: U.S. EPA 
Headaquarters Library, Washington, D.C.) 

Lindgren, A.; Vahter, M.; Dencker, L. (1982) Autoradiographic studies on the 
distribution of arsenic in mice and hamsters administered 74As-arsenite 
or -arsenate. Acta Pharmacol. Toxicol. 51:253-265. 

Lovell, M.A.; Farmer, J.G. (1985) Arsenic speciation in urine from humans 
intoxicated by inorganic arsenic compounds. Hum. Toxicol. 4:203-214. 

Lubin, J.H.; Pottern, L.M.; Blot, W.J.; Tokudome, S.; Stone, B.J.; Fraumeni, 
J.F. Jr. (1981) Respiratory cancer among copper smelter workers: recent 
mortality statistics. JOM 23:779-784. 

Luchtrath, H. (1972) Liver cirrhosis due to chronic arsenic intoxication in 
vintners. Dtsch. Med. Wochenschr. 97:21-22. 

Mahieu, P.; Buchet, J.P.; Reels, H,; Lauwerys, R. (1981) The metabolism of 
arsenic in humans acutely intoxicated by AS 2 O 3 : its significance for the 
duration of BAL therapy. Clin. Toxicol. 18:1067-1075. 

MacMahon, B.; Pugh,T. (1970) Epidemiology-principles and methods. 
Boston, MA: Little, Brown and Co., p. 65-66. 


119 


Marafante, E.; Vahter, M. (1984) The effect of methyltransferase inhibition on 
the metabolism of [^Ms] arsenite in mice and rabbits. Chem. Biol. 
Interact. 50:49-57. 

Marafante, E.; Vahter, M., Envall _. (1985) The role of the 

methylation in the detoxification of arsenate in the rabbit. Chem. Biol. 
Interact. 56:225-238. 

Marafante, E.; Vahter, M. (1986) The effect of dietary and chemically induced 
methylation deficiency on the metabolism of arsenate in the rabbit. Acta 
Pharmacol. Toxicol. 58 Supplement II. 

Marafante, E.; Vahter, M. (1987) Solubility, retention and metabolism of 
intratracheally and orally administered inorganic arsenic compounds in 
the hamster. Environ. Res. 42: (in press). 

Montgomery, H. (1935) Arch. Derm. Syph. 32:229 (as cited in Neubauer, 
1947). 

Morris, J.M.; Schmid, M.; Newman, S.; Scheuer, P.J.; Sherlock, S. (1974) 
Arsenic and noncirrhotic portal hypertension. Gastroenterology 64:86- 
94. 

Morton, W.; Starr, G.; Pohl, D.; Stoner, J.; Wagner, S; Weswig, P. (1976) Skin 
cancer and water arsenic in Lane County, Oregon. Cancer 37:2523- 
2532. 

Nagy, G.; Nemeth, A.; Bodor, F.; Ficsor, E. (1980) Cases of bladder cancer 
caused by chronic arsenic poisoning. Orv. Hetil. 121:1009-1011. 

National Academy of Sciences, NAS, (1977) Arsenic. Washington, D.C.: 
National Academy Press. 

National Academy of Sciences NAS (1983) Drinking water and health. 
Washington, DC: National Academy Press. 

Neubauer, 0. (1947) Arsenical cancer: a review. Br. J. Cancer 1:192-251. 

Nordenson, 1.; Sweins, A.; Beckman, L. (1981) Chromosome aberrations in 
cultured human lymphocytes exposed to trivalent and pentavalent 
arsenic. Scand J. Work Environ. Health 7:277-281. 

Nurse, D.S. (1978) Hazards of inorganic arsenic. Med. J. Aust. 1:102. 

Occupational Safety and Health Administration (OSHA) (1986) Occupational 
safety and health standards, inorganic arsenic. 29 CFR Ch.XVBII, Part 
1910.1018. 

O’Connor, T.P.; Campbell, T.C. (1985) Essentiality of the trace element 
arsenic. Final report. Prepared for the Carcinogen Assessment Group, 
Office of Health and Environmental Assessment, D.S. Environmental 
Protection Agency, Washington, D.C. Unpublished. Available from: U.S. 
EPA Headquarters Library, Washington, D.C. 

Office of Science and Technology Policy (OSTP) (1985) Chemical 
carcinogens: review of the science and its associated principles. Federal 
Register 50:10372-10442. 

Pershagen, G.; Vahter, M. (1979) Arsenic. National Swedish Environment 
Protection Board (SNV PM 1128), Stockholm. 

Phillip, R.; Hughes, A.O.; Robertson, M.C.; Mitchell, T.F. (1983) Malignant 
melanoma incidence and association with arsenic. Bristol Med. Chir J 
98(368):165-169. 

Podgor, M.; Leske, C. (1986) Estimating incidence from age-specific 
prevalence for irreversible diseases with differential mortality. Statistics in 
Medicine 5:573-578. 


120 



Poma, K.; Degraeve, N.; Kirsch-Volders, M. (1981) A combined action of 
arsenic and ethyl methanesulfonate (EMS) in somatic and germ cells of 
mice. Mutat. Res. 85:295. 

Popper, H.; Thomas. L.B.; Telles. N.C.; Falk, H.; Selikoff, I.J. (1978) 
Development of hepatic angiosarcoma in man induced by vinyl chloride, 
thorotrast, and arsenic. Am. J. Pathol. 92:349-376. 

Prunes, L. (1946) Regional chronic hyperkeratosis in Pisagua (as cited in 
Zaldivar, 1974). 

Prystowsky, S.D.; Elfenbein, G.J.; Lamberg, S.l. (1978) Nasopharyngeal 
carcinoma associated with long-term arsenic ingestion. Arch. Dermatol. 
114:602-603. 

Regelson, W.; Kim, U.; Ospina, J.; Holland, J.F. (1968) Hemangioendothelial 
sarcoma of liver from chronic arsenic intoxication by Fowler’s solution. 
Cancer 21:514-522. 

Reymann, F.; Moller, R.; Nielsen, A. (1978) Relationship between arsenic 
intake and internal malignant neoplasms. Arch. Dermatol. 114:378-381. 

Reynolds, E.S. (1901) An account of the epidemic outbreak of arsenical 
poisoning occurring in beer drinkers in the north of England and the 
midland counties. Lancet January 19, pp. 166-170. 

Riggan, W.B.; Van Bruggen, J.V.; Acquavella, J.F.; Beaubler, J.; Mason, T. 
(1983) U.S. cancer mortality rates and trends, 1950-1979. Joint 
publication of the U.S. Environmental Protection Agency and the National 
Cancer Institute, Vol. II. EPA-600/1-83-015a, pp. 435-505. 

Roat, J.W.; Wald, A.; Mendelow, H.; Pataki, K.l. (1982) Hepatic angiosarcoma 
associated with short-term arsenic ingestion. Am. J. Med. 73:933-936. 

Robson, A.O.; Jelliffe, A.M. (1963) Medicinal arsenic poisoning and lung 
cancer. Br. Med. J. (ii)207-209. 

Rosset, M. (1958) Arsenical keratoses associated with carcinomas of the 
internal organs. Can. Med. Assoc. J. 78:416-419. 

Rossman, T.G. (1981) Enhancement of UV-mutagenesis by low 
concentrations of arsenite In Escherichia coli. Mutat. Res. 91:207-211. 

Roth, F. (1956) Concerning chronic arsenic poisoning of the Moselle wine 
growers with special emphasis on arsenic carcinomas. Z. Krebsforschung 
61:287-319. 

Roth, F. (1957) Concerning the delayed effects of chronic arsenic of the 
moselle wine growers. Dtsch. Med. Wochenschr. 82:211-217. 

Salcedo, J.C.: Portales, A.; Landecho, E.; Diaz R. (1984) Transverse study of 
a group of patients with vasculopathy from chronic arsenic poisoning in 
communities of the Francisco I. Madern and San Pedro Districts, 
Coahulla, Mexico. Revista de la Facultad ae Medicina de Torreon, pp. 
12-16. 

Sanchez de la Fuente, E. (Undated) Chronic arsenicalism in the rural area of 
the lake district, 1962-1964. Report prepared for the Administration of 
Public Health Services in States and Territories of Mexico. 13 pp. 

Sanderson, K.V. (1976) Arsenic and skin cancer. In: Andvade, R.; Quinport, 
S.L.; Popkin, G.L.; Res, T.D., eds. Cancer of the skin, Vol. 1. Biology, 
diagnosis management. Philadelphia, PA. W.B. Saunders and Co., pp. 
473-491. 


121 


Schmidt, A.; Anke, M.; Groppel, B.; Kronemann, H. (1984) Effects of As- 
deficiency on skeletal muscle, myocardium and liver: a histochemical and 
ultrastructural study. Exp. Pathol. 25:195-197. 

Scotto, J.; Fraumeni, J. Jr. (1982) Chapter 60: Skin (other than melanoma). In: 
Cancer epidemiology and prevention. Philadelphia, PA: W.B. Saunders 
and Co., pp. 996-1011. 

Scotto, J.; Fecus, T.; Fraumeni, J. Jr. (1983) Incidence of nonmelanoma skin 
cancer in the U.S. U.S. Department of Health and Human Services. NIH 
publication no. 83-2433. 

Shannon, R.L.; Strayer, D.S. (1987) Arsenic-induced skin toxicity. Report 
prepared for the Office of Health and Environmental Assessment under 
EPA contract no. 68-02-4131. (Available from: U.S. EPA Headquarters 
Library, Washington, DC. 

Shivapurkar, N.; Poirier, L.A. (1983) Tissue levels of S-adenosylmethionine 
and S-adenosylhomocysteine in rats fed methyl-deficient, amino 
acid-defined diets for one to five weeks. Carcinogenesis 4:1051. 

Smith, T.J.; Creceluis, E.A.; Reading, J.C. (1977) Airborne arsenic exposure 
and excretion of methylated arsenic compounds. Environ. Health 
Perspect. 19:89-93. 

Sommers, S.C.; McManus, R.G. (1953) Multiple arsenical cancers of the skin 
and internal organs. Cancer 6:347-359. 

Southwick, J.W.; Western, A.E.; Beck, M.M.; Whitley, T.; Isaacs, R.; Petajan, 
J; Hansen, C.D. (1983) An epidemiolgoical study of arsenic in drinking 
water in Millard County, Utah. In: Lederer, W.; Fensterheim, R., eds. 
Arsenic: industrial, biomedical, and environmental perspectives. New 
York, NY: Van Nostrand Reinhold, pp. 210-225. 

Sram, R.F. (1976) Relationship between acute and chronic exposure in 
mutagenicity studies in mice. Mutat. Res. 41:25-42. 

Tam, G.K.H., Charbonneau, S.M.; Bryce, F.; Pomroy, C.; Sandi, E. (1979). 
Metabolism of inorganic arsenic (^^As) in humans following oral 
ingestion. Toxicol. Appl. Pharmacol. 50:319-322. 

Tovar, E.; Chavez, A.; Perez Hidalgo, C.; Garmilla, M. (1964) Studies in a 
community with chronic endemic arsenicalism. ill. Ingestion and excretion 
of arsenic. Salud. Publica. Mex. 6(3):443-449. 

Tseng, W.-P. (1977) Effects and dose-response relationships of skin 
cancer and Blackfoot disease with arsenic. Environ. Health Perspect. 
19:109-119. 

Tseng, W.-P.; Chu, H.M.; How, S.W.; Fong, J.M.; Lin, C.S.; Yen, S. (1968) 
Prevalence of skin cancer in an endemic area of chronic arsenicism in 
Taiwan. J. Natl. Cancer Inst. 40(3):453-463. 

U.S. Bureau of the Census. (1987) Estimates of the population of the United 
States by age, sex, and race: 1980-1986. 

U.S. Environmental Protection Agency (EPA). (1984a) Health assessment 
document for inorganic arsenic. Final report. Office of Health and 
Environmental Assessment. EPA-600/8-83-021F. NTIS PB84- 
190891. 

U.S. Environmental Protection Agency (EPA). (1984b) Office of Drinking 
Water. Arsenic occurrence in drinking water, food, and air. September 27. 

U.S. Environmental Protection Agency (EPA). ( 1985) Office of Drinking Water 
proposed rulemaking on arsenic. Federal Register 50:46959-46961. 


122 


U.S. Environmental Protection Agency (EPA). (1986) Guidelines for 
carcinogen risk assessment. Federal Register 51:33992-34003. 

U.S. Environmental Protection Agency (EPA). (1987) Risk Assessment Forum 
workshop on arsenic. Summary report of a workshop held in December 
1986. Available from: U.S. EPA Headquarters Library, Washington, DC. 

Uthus, E.O.; Nielsen, F.H. (1985) Effects in chicks of arsenic, arginine, and 
zinc and their interaction on body weight, plasma uric acid, plasma urea, 
and kidney arginase activity. Biological Trace Element Research 7:11- 
20 . 

Uthus, E.O.; Cornatzer, W.E.; Nielsen, F.H. (1983) Consequence of arsenic 
deprivation in laboratory animals. In: Lederer, W.H.; Fensterheim, R.J., 
eds. Arsenic: industrial, biomedical, and environmental perspectives. New 
York, NY: Van Nostrand Reinhold, pp. 173-189. 

Vahter, M. (1983) Metabolism of arsenic. In: Fowler, B.A., ed. Biological and 
environmental effects of arsenic. Amsterdam: Elsevier, Chapter 5. 

Vahter, M. (1986). Environmental and occupational exposure to inorganic ^ 
arsenic. Acta Pharmacol. Toxicol. 59:31-34. 

Vahter, M.; Envall, J. (1983) In vivo reduction of arsenate in mice and rabbits. 
Environ. Res. 32:14-24. 

Vahter, M.; Marafante, E. (1983) Intercellular interaction metabolic fate of 
arsenite and arsenate in mice and rabbits. Chem. Biol. Interact. 47:29- 
44. 

Vahter, M.; Marafante, E. (1985) Reduction and binding of arsenate in 
marmoset monkeys. Arch. Toxicol. 57:119-124. 

Vahter, M.; Marafante, E.; Dencker, L. (1984) Tissue distribution and retention 
of 74As-dimethylarsenic acid in mice and rats. Arch. Environ. Contam. 
Toxicol. 13:259-264. 

Valentine, J.; Kang, H.; Spivey, G. (1979) Arsenic levels in human blood, urine 
and hair in response to exposure via drinking water. Environ. Res. 
20:24-32. 

Wagner, S.L.; Maliner, J.; Morton, W.E.; Braman, R.S. (1979) Skin cancer and 
arsenical intoxication from well-water. Arch. Dermatol. 115:1205-1207. 

Watson, G. (1977) Age incidence curve for cancer. Proc. Natl. Acad. Sci. 
74:1341-1342. 

Weiler, R.R. (1987) Unpublished data. Ministry of the environment, report no. 
87-48-45000-057, Toronto, Ontario. Available from: U.S. EPA 
Headquarters Library, Washington, DC. 

Welch, K.; Higgins, 1.; Oh, M.; Burchfield, C. (1982) Arsenic exposure, 
smoking, and respiratory cancer in copper smelter workers. Arch. 
Environ. Health 37:325-335. 

Whittemore, A. (1977) The age distribution of human cancer for carcinogenic 
exposures of varying intensity. Am. J. Epidemiol. 106:418-432. 

Whittemore, A.; Keller, B. (1978) Quantitative theory of carcinogenesis. 
Society Ind. Appl. Math. Review 20:1-30. 

World Health Organization. (WHO, 1981) Environmental health criteria 18: 
Arsenic: international programme on chemical safety, Geneva, pp. 63, 
127-129. 

Yamashita. N.; Doi, M.; Nshio, M.; Hojo, H.; Masato, T. (1972) Current state of 
Kyoto children poisoned by arsenic tainted Morinaga dry milk. Japanese 
J. Hyg. 27(4):364-399. 


123 


Yamauchi, H.; Yamamura, Y. (1984) Metabolism and excretion of orally 
ingested trimethylarsenic in man. Bull. Environ. Contam. Toxicol. 
32:682-687. 

Yeh, S. (1973) Skin cancer in chronic arsenicism. Human Pathol. 4(4): 469- 
485. 

Yeh, S.; How, S.W.; Lin, C.S. (1968) Arsenical cancer of skin-histologic study 
with special reference to Bowen’s disease. Cancer 21 (2):312-339. 

Yue-zhen, H.; Xu-chun, Q.; Guo-quan, W.; Bi-yu, E.; Dun-ding, R.; 
Zhao-yue, F.; Ji-yao, W.; Rong-jiang; X.; Feng-e, Z. (1985) Endemic 
chronic arsenicism in Xinjiang. Chin. Med. J. 98(3):219-222. 

Zaldivar, R. (1974) Arsenic contamination of drinking water and foodstuffs 
causing endemic chronic poisoning. Beitr. Pathol. 151:384-400. 

Zalidvar, R. (1977) Ecological investigations on arsenic dietary intake and 
endemic chronic poisoning in man: dose-response curve. Zentralbl. 
Bakteriol. Parasitenkd. Infektionskr. Hyg. Abt. 1: Oriq. Reihe B. 164: 
481-484. 

Zaldivar, R.; Guillier, A. (1977) Environmental and clinical investigation on 
epidemic chronic arsenic poisoning in infants and children. Zentralbl. 
Bakteriol. Parasitenkd. Infektionskr. Hyg. Abt. 1: Grig. Reihe B. 165:226- 
243. 



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